The dwarf planet Ceres keeps looking better and better as a possible home for alien life.
NASA’s Dawn spacecraft has spotted organic molecules — the carbon-containing building blocks of life as we know it — on Ceres for the first time, a study published today (Feb. 16) in the journal Science reports.
And these organics appear to be native, likely forming on Ceres rather than arriving via asteroid or comet strikes, study team members said.
“Because Ceres is a dwarf planet that may still preserve internal heat from its formation period and may even contain a subsurface ocean, this opens the possibility that primitive life could have developed on Ceres itself,” Michael Küppers, a planetary scientist based at the European Space Astronomy Centre just outside Madrid, said in an accompanying “News and Views” article in the same issue of Science.
“It joins Mars and several satellites of the giant planets in the list of locations in the solar system that may harbor life,” added Küppers, who was not involved in the organics discovery.
The $467 million Dawn mission launched in September 2007 to study Vesta and Ceres, the two largest objects in the main asteroid belt between Mars and Jupiter.
Dawn circled the 330-mile-wide (530 kilometers) Vesta from July 2011 through September 2012, when it departed for Ceres, which is 590 miles (950 km) across. Dawn arrived at the dwarf planet in March 2015, becoming the first spacecraft ever to orbit two different bodies beyond the Earth-moon system.
During its time at Ceres, Dawn has found bizarre bright spots on crater floors, discovered a likely ice volcano 2.5 miles (4 km) tall and helped scientists determine that water ice is common just beneath the surface, especially near the dwarf planet’s poles.
The newly announced organics discovery adds to this list of achievements. The carbon-containing molecules — which Dawn spotted using its visible and infrared mapping spectrometer instrument — are concentrated in a 385-square-mile (1,000 square km) area near Ceres’ 33-mile-wide (53 km) Ernutet crater, though there’s also a much smaller patch about 250 miles (400 km) away, in a crater called Inamahari.
And there could be more such areas; the team surveyed only Ceres’ middle latitudes, between 60 degrees north and 60 degrees south.
“We cannot exclude that there are other locations rich in organics not sampled by the survey, or below the detection limit,” study lead author Maria Cristina De Sanctis, of the Institute for Space Astrophysics and Space Planetology in Rome, told Space.com via email.
Dawn’s measurements aren’t precise enough to nail down exactly what the newfound organics are, but their signatures are consistent with tar-like substances such as kerite and asphaltite, study team members said.
“The organic-rich areas include carbonate and ammoniated species, which are clearly Ceres’ endogenous material, making it unlikely that the organics arrived via an external impactor,” co-author Simone Marchi, a senior research scientist at the Southwest Research Institute in Boulder, Colorado, said in a statement.
In addition, the intense heat generated by an asteroid or comet strike likely would have destroyed the organics, further suggesting that the molecules are native to Ceres, study team members said.
The organics might have formed via reactions involving hot water, De Sanctis and her colleagues said. Indeed, “Ceres shows clear signatures of pervasive hydrothermal activity and aqueous alteration,” they wrote in the new study.
Such activity likely would have taken place underground. Dawn mission scientists aren’t sure yet how organics generated in the interior could make it up to the surface and leave the signatures observed by the spacecraft.
“The geological and morphological settings of Ernutet are still under investigation with the high-resolution data acquired in the last months, and we do not have a definitive answer for why Ernutet is so special,” De Sanctis said.
It’s already clear, however, that Ceres is a complex and intriguing world — one that astrobiologists are getting more and more excited about.
“In some ways, it is very similar to Europa and Enceladus,” De Sanctis said, referring to ocean-harboring moons of Jupiter and Saturn, respectively.
“We see compounds on the surface of Ceres like the ones detected in the plume of Enceladus,” she added. “Ceres’ surface can be considered warmer with respect to the Saturnian and Jovian satellites, due to [its] distance from the sun. However, we do not have evidence of a subsurface ocean now on Ceres, but there are hints of subsurface recent fluids.”
The discovery is considered a key piece of evidence for a critical, but poorly understood period of time when the universe switched from being dark to radiating light.
Scientists theorize that energy from first-generation galaxies transformed the dark, electrically neutral universe into ionized and radiating plasma. But these faint galaxies are not easy to find.
This week, University of Texas astronomer Rachael Livermore and colleagues describe a successful hunt thanks to a new technique that combines deep-field Hubble Space Telescope images with what is known as “wavelet decomposition” — a light-masking equivalent of noise-canceling headphones — to computationally remove light from foreground galaxy clusters.
“The wavelet transform allows us to decompose an image into its components on different physical scales. Thus, we can isolate structures on large scales… and remove them, allowing objects on smaller scales to be identified more easily,” the scientists wrote in a draft of their upcoming paper, published on arXiv.org.
Ironically, astronomers first have to rely on galaxy clusters, which warp spacetime with their massive gravity, to serve as naturally occurring lenses that boost Hubble’s resolving power more than 100 times.
By then masking the light, Livermore, University of Texas astronomer Steven Finkelstein and Space Telescope Science Institute astronomer Jennifer Lotz found 167 galaxies that are 10 times fainter than any previously known, a number that shows “strong support” for how many early galaxies would have been needed to re-ionize the universe.
A more direct detection method will come after Hubble’s successor, the James Webb Space Telescope, is launched next year.
For decades, astronomers have tracked black holes with masses millions of times that of the sun, as well as those with tens of solar masses. But black holes between those two extremes have proved elusive. Now, astronomers studying a globular cluster have found just such a black hole at its center, showing that intermediate-mass black holes could be hiding out in these compact agglomerations of stars.
Lead study author Bülent Kiziltan, an astronomer at the Harvard-Smithsonian Center for Astrophysics (CfA), and his co-authors Holger Baumgardt (of Australia’s University of Queensland) and Abraham Loeb (also of CfA) found a black hole between 1,400 and 3,700 solar masses at the center of 47 Tucanae, a globular cluster in the southern sky some 16,700 light-years from Earth.
Black holes are usually found because they emit massive amounts of X-rays as matter falls in. Midsize black-hole candidates have been found in galaxies; a group from the University of Maryland and NASA’s Goddard Space Flight Center found one in another galaxy in 2015, and there are about a dozen objects in total.
Kiziltan and his team found this one by measuring motions of pulsars within the cluster. They found the telltale signs of a compact, massive object in the cluster’s heart. The likeliest explanation for the motions was a black hole.
“Intermediate-mass black holes have been expected [in globular clusters] for many decades,” Kiziltan told Space.com. “But we’ve not been able to find one conclusively.”
Theorists think stellar-mass black holes form from stars that are at least a few dozen times the mass of the sun. When they run out of nuclear fuel, there is no longer enough energy from radiation to hold the star’s outer layers against its immense gravity. The star collapses, and then explodes as a supernova. (Supernovas can outshine the galaxies in which they reside.) What’s left of the star then shrinks into a tiny volume. A 100-solar-mass star, as a black hole, would have a radius of about 180 miles (290 kilometers). The former star’s escape velocity exceeds that of light, resulting in a black hole, from which nothing can escape.
A big question for astronomers is what the population of black holes looks like. Given that there are supermassive black holes, and stellar-mass ones, there should be a population of black holes with masses between those two. But there don’t seem to be as many as expected. The centers of globular clusters, which are agglomerations of old stars, seemed a good place to look, as earlier studies indicated they might be there, according to the new study.
The problem is, black holes are visible only when stuff falls in them. As such, the researchers needed another method that didn’t depend on picking up radio emissions.
That’s why Kiziltan and his colleagues decided to look at the pulsars that inhabit a globular cluster. Pulsars form from stars less massive than those that make black holes. After those stars go supernova, they collapse into neutron stars
Some neutron stars spin rapidly and emit radio waves along a line offset from their rotational axes. These are called pulsars. Earthbound observers see them if Earth is in the radio beam as it sweeps across the sky. Pulsars’ rotation rates change so little that they are precise timekeepers. They are precise enough that by timing the signal and looking for any Doppler shifts, it’s possible to measure a pulsar’s movement along one’s line of sight.
Kiziltan’s group tracked the movement of some two dozen pulsars and used computer simulations to model the cluster to track down their black-hole candidate.
“We’re proposing a brand-new approach to the study of globular clusters,” Kiziltan said. “It’s not only that we see the dynamical signature of a black hole, but how to probe the region near it without going too close to it.” Probing the centers of globular clusters is usually difficult, because the density of stars makes it hard to see what’s going on.
Finding the intermediate-mass black hole raises more questions about how these black holes form, said Cole Miller, a professor of astronomy at the University of Maryland who studies black-hole formation. “Let’s say it’s an intermediate-mass black hole,” he said. “How did it get there?”
“Globular clusters have small escape speeds,” he said. “So the stars should blow away all the gas.” There will be some as stars age, such as a red giant’s stellar winds. “But that amount of gas is nowhere close enough to make an intermediate-mass black hole.”
This differs from the supermassive black holes at galactic centers, he added, because one would expect lots of matter to accumulate there, feeding a black hole and allowing it to grow very fast.
Both Kiziltan and Cole said there are several ways to grow black holes early in a cluster’s history. “One of my favorites is runaway collisions of stars or stellar- mass black holes,” Miller said. “An interesting effect is, if you have a bunch of stars in a dense stellar region, the heaviest will start runaway collisions.” Once a black hole forms — perhaps when a star that’s absorbed a few neighbors dies ― all the matter that isn’t in a stable orbit around the black hole will fall in or get ejected from the cluster, he said. That puts an automatic stop on the black hole’s growth.
For scientists to get a better handle on how such black holes might form in clusters, more of them need to be found — but that won’t be easy, Kiziltan said. The only reason it worked for 47 Tucanae was that there were enough pulsars in it to begin with, and they were close enough to see. Not every globular cluster has the right combination of distance and bright pulsars.
The wandering black hole was discovered lurking just outside a supernova remnant, a shell of expelled material left behind after a massive star explodes. Using the Atacama Submillimeter Telescope Experiment (ASTE) in Chile and the 45-meter (148 feet) Radio Telescope at Nobeyama Radio Observatory, astronomers found that the black hole had been previously hidden by a compact gas cloud emerging from the remnant.
The cloud itself has now been named “the Bullet,” because of its long, cone shape and its incredible speed — part of the cloud is moving away from the supernova remnant at more than 60 miles per second [100 kilometers per second], “which exceeds the speed of sound in interstellar space by more than two orders of magnitude,” Nobeyama Radio Observatory scientists said in the statement. The researchers now suspect that the black hole might have played a role in forming the gaseous “bullet.”
The supernova remnant, called W44, is located 10,000 light-years from Earth. The Bullet, which is about 2 light-years long [11.76 trillion miles, or 18.9 trillion km], is so energetic that it moves backward against the rotation of the Milky Way galaxy, according to the Nobeyama Radio Observatory statement.
“Most of the Bullet has an expanding motion with a speed of 50 km/s [31 miles per second], but the tip of the Bullet has a speed of 120 km/s [75 miles per second],” Masaya Yamada, lead author of the new study and a graduate student at Keio University in Japan, said in the statement. “Its kinetic energy is a few tens of times larger than that injected by the W44 supernova. It seems impossible to generate such an energetic cloud under ordinary environments.”
So what could possibly send such a huge amount of molecular gas streaming out of the supernova remnant at such high speeds? The discovery of the hidden black hole may offer an explanation.
The researchers developed two possible scenarios for how the Bullet might have formed. The first, called the explosion model, suggests that the cloud passed by a static black hole and was pulled in by the black hole’s strong gravitational forces. This could have created a powerful explosion of gas that was spit back out into space, Nobeyama scientists said.
Another theory, called the irruption model, proposes that a high-speed black hole tore through the dense molecular cloud, and the black hole’s powerful gravitational pull left a stream of gas in its wake. Further research is required to determine which model best explains the origin of the Bullet, according to the study, published Dec. 29, 2016, in The Astrophysical Journal Letters.
Although millions of black holes are thought to exist in the Milky Way, it is often difficult to locate them because they are completely black. However, this study has revealed a new way for astronomers to detect these types of elusive, stray black holes — by their influence on molecular gas clouds — that would otherwise float alone in space and remain unnoticed with no observable emissions, the scientists said in the statement.
Wormholes are a workhorse of sci-fi interstellar civilizations in books and on the screen because they solve the annoying problem of “Well, if we stuck to known physics, 99.99999 percent of the story would be as fascinating as watching people sleep.”
But could we do it? Could we actually warp and bend space-time to make a convenient tunnel, making all of our galactic dreams come true?
The concept of wormholes got its start when physicist Ludwig Flamm, and later Albert Einstein and Nathan Rosen, realized that black holes can be “extended.” When one goes about solving the fantastically complicated equations of general relativity, the machinery that predicts a black hole also predicts a phenomenon called a white hole. A white hole is pretty much what you think: Whereas a black hole’s event horizon marks a region of space that once you enter you can’t leave, it’s impossible to enter a white hole’s horizon, although anything already in there can escape.
That same mathematical machinery delivers a bonus, too: All black holes would be naturally “connected” to white holes via their singularities, making a tunnel through space. Woohoo, wormholes here we go!
Or not. While we have gobs of evidence for the existence of black holes, white holes appear to be mathematical fiction. There’s no known process in our universe that would actually form them, and even if they did pop into existence, their natural extreme instability would snuff them right out again.
Oh, yeah, and the mechanism for making black holes — the collapse of massive stars — also automatically prevents the formation of a symbiotic white hole.
And even if they did form (and they don’t), the extreme gravity of the mutual singularities would cause the wormhole tunnel to immediately stretch and snap much more quickly than anything could cross it.
Death by wormhole
But that doesn’t stop anybody from playing a fun game of “what if.” What if white holes could naturally form, or be constructed? What if we could stabilize them? What if we could attach a white hole’s singularity to a black hole and make a wormhole? What if? What if? What if?
Well, for one thing, traveling down such a wormhole would really, really suck. Literally. The entrance to the wormhole — the “throat” — sits inside the event horizon of the black hole.
That’s a problem.
The very definition of an event horizon — their very cosmique raison d’etre — is that once you enter them, you don’t get to come out. No way, no how. It doesn’t matter if there’s a wormhole tunnel inside it — you don’t get to leave.
Inside a black hole event horizon, you have only one destination: singularity town, the place of infinite density and soul-crushing gravitational forces.
So let’s say you enter a wormhole. You can watch light from another patch of the universe filter in from the opposite side. If someone else jumps in, you can meet them and have some tea together. And you can die — miserably — as you careen into the singularity.
Is there any way to make a working, even fun, wormhole, instead of a terrifying portal to inevitable destruction?
Surprisingly, yes. Well, not quite 100 percent absolutely “this is a normal part of our universe” yes. More like “if we play pretend” yes.
To construct a traversable wormhole, you need to overcome two important obstacles. First, the entrance to the wormhole has to actually sit outside the event horizon. That would allow you to enter the wormhole and blast through it to your faraway destination without fearing a “singular” encounter.
Second, the tunnel itself has to be stable and strong. It has to withstand the extreme gravity of the singularities and resist tearing apart when something flies down its length.
There is indeed a material that solves both problems. But that material has a problem all its own: It has negative mass.
That’s right: mass, but negative. A ring of negative-mass material could be used to construct a fully functional and useful wormhole. Since the exotic nature of negative mass warps spacetime in a unique way, it “inflates” the entrance to the wormhole outside the boundary of the event horizon, and stabilizes the throat of the wormhole against instabilities. It’s not an intuitive result but the math checks out.
But could such a substance exist? We’ve mapped out a good chunk of the universe, and we’ve never seen negative mass. If it did exist, it would have some pretty weird properties. For example, following the math of Newton’s Laws with some minus signs tossed in, we find that a negative-mass particle would push on a positive-mass particle, while the positive-mass particle would pull on the negative-mass one. Set two opposite-mass particles next to each other, perfectly still, and the pair would start accelerating, zooming off without any input of force.
What about the Casimir effect, the odd and fascinating attraction of two metal plates due to vacuum energy? That’s often trotted out as an example of the universe behaving badly, and a possible route to negative mass. But the Casimir force is characterized by local negative pressure (it pulls rather than pushes), not negative mass.Sure, we don’t know everything there is to know about quantum gravity and the nature of space-time at super-duper-teensy scales. Could an advanced civilization discover the path to negative mass and manipulate gravity in just the right way? Would a breakthrough in physics point a way to fashioning wormholes?
Honestly, probably not. There are just too many things working against them. Working wormholes would violate so many aspects about known (and extremely well tested) physics that I think it’s better to just work on other problems.
I know some people might accuse me of not being creative enough, but the universe doesn’t care about our creativity. The tools of science are harsh but fair judges; if an idea doesn’t work, it simply doesn’t work. There are many varied and beautiful mysteries in our universe, and we certainly haven’t unlocked all of the inner workings of the cosmos. But wormholes probably aren’t one of them.
Alpha Centauri is having a moment: Our mysterious neighboring star system has been seeing a surge of scientific interest lately, and for good reason.
Although space researchers have often focused on our own galaxy, Alpha Centauri has become a more viable option to closely study, and even potentially travel to one day. Our nearest stellar neighbor has received a lot of buzz recently due to the announcement of Breakthrough Starshot, a mission backed by famed cosmologist Stephen Hawking, Russian investor Yuri Milner and Facebook CEO Mark Zuckerberg, with the goal of sending probes to Alpha Centauri someday.
Although it’s the closest star system to our sun, Alpha Centauri is still 4.37 light-years (25 trillion miles, or 40 trillion kilometers) away from Earth. Because it’s so far away, reaching and studying Alpha Centauri poses significant challenges. But the three-star system — comprising Alpha Centauri A, Alpha Centauri B and a faint red dwarf star Proxima Centauri — also presents enormous opportunities for furthering space research, which is why it is the focus of our mission at Project Blue.
NASA’s Kepler space telescope has found thousands of exoplanets in the universe, many of which orbit in the habitable zones of their stars and could be Earth-like. In fact, one out of every two sun-like stars has a rocky, potentially Earth-like planet in its habitable zone. At Project Blue, we are aiming to actually see one with our own eyes — and take the first photograph of a planet like Earth.
So, why focus on Alpha Centauri? In short, it gives us the best opportunity to accomplish our mission.
A large reason for this is its proximity. After Alpha Centauri, the next-closest sun-like star is 2.5 times farther away and would require a telescope 2.5 times larger in order to be viewed at the same level of detail.
The system also has a unique binary structure: It contains not just one, but two stars similar to the sun, doubling our chances of finding planets in either of their habitable zones. In fact, that gives us an estimated 85 percent probability that the Alpha Centauri system harbors at least one potentially habitable planet. However, although the binary structure increases our odds, it also presents challenges. In order to take the photograph, we have to use a specialized system to efficiently suppress the light of two stars to see any potential surrounding planets.
Finally, the last reason our focus remains on our neighboring star system is that Alpha Centauri A is a yellow “G2”-type star that has a temperature and color that closely match the sun’s, thus increasing the chances of the existence of an Earth-like planet. Alpha Centauri B, which is a bit cooler and redder than our sun, is also still a good candidate to host a rocky planet like Earth.
The image we hope to take would reveal whether the planet appears blue, as Earth does from space, which could suggest that it hosts liquid oceans or a substantial atmosphere — and, therefore, the potential to support life.
Our chances of spotting a planet successfully are high in Alpha Centauri. This is only underscored by the discovery of an Earth-like planet in the star system earlier this year. Scientists have located the planet Proxima b, with a minimum mass 1.3 times that of Earth, orbiting in the habitable zone of its star, Proxima Centauri.
This recent discovery is indeed exciting, and it sparked Breakthrough Starshot to announce that it will focus on the potential to travel to Proxima b one day, once the technology is developed. However, the planet is not a good option for Project Blue. Because Proxima b orbits so closely to its small, dim star, it would be extremely difficult to image with a telescope, and as such, our focus remains on the larger stars Alpha Centauri A and B.
Alpha Centauri’s potential is exciting to not only the science community but the future of humanity, and it’s clear that it will provide us with some of our most exciting space discoveries in the years to come.
As astronomers work to learn more about the environment it, a new paper in Astrophysical Journal Letters makes predictions about what would happen to young, highly magnetized stars in Sgr A*’s vicinity. It’s the first time a star’s magnetic field has been included in simulations where a black hole tidally disrupted a star, meaning the star is pulled apart and stretched.
“Magnetic fields are a bit tricky numerically to simulate,” James Guillochon, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, told Seeker. In the past, it’s been hard to put magnetic fields in context with other influences on a star, such as gas pressure and gravity. This is especially true towards the boundary or atmosphere of the star.
The simulations show that if a star gets a “glancing blow” from a black hole, it can survive the encounter and its magnetic field amplifies strongly, by a factor of about 30. But if the star gets very close to the black hole, the star is tidally destroyed and the magnetic field maintains its strength.
“One of the immediate impacts is that we might see highly magnetized stars in the centers of galaxies, and that includes our own galactic center,” Guillochon added. “We also would expect this to affect the resulting flare that arises from the disruption of the star by the supermassive black hole. Half the matter of the star falls on to the black hole and feeds it, and that generates a luminous flare of a billion or 10 billion solar luminosities.”
A star disruption should theoretically be visible in our own galactic center, but Guillochon says that only happens about once every 10,000 years or so. Luckily, the stream of the disrupted star can persist for centuries, feeding the black hole.
Guillochon co-wrote a paper a couple of years ago about G2, a gas cloud falling into the galactic center in 2014 that produced far less activity than expected. It suggests that G2 could have been produced by the disruption of a red giant star, and its gas envelope is still feeding the black hole today.
He suggested that G2-like clouds would form by “clumping up” due to cooling instabilities, which would put regular deliveries of a G2-type cloud once every decade. When the material is highly magnetized, co-author Michael McCourt has previously suggested that the fields can help stabilize the clouds and prevent them from breaking apart. If the pattern holds true, highly magnetized clouds would continue to pass near the black hole over the next several decades.
That said, the challenge of learning about stars that survive disruption in the galactic center is they tend to be lower mass and hard to see. How many of them are magnetized, and how strongly, remains an open question, Guillochon said. Below is a short animation simulating a star’s magnetic field being torn apart by a black hole.
It’s always an exciting time to be involved in space exploration, and 2017 has already proved to be no exception. At Project Blue, we’re on a mission to find and photograph an Earth-like planet around Alpha Centauri — and as you probably saw in the news recently, we’re not the only ones with that ambitious goal. Breakthrough Initiative, a private organization aimed at looking for other life, announced it also wants to search for planets in Earth’s neighboring star system, and that group will tap the best telescopic technology in Chile in hopes of doing so.
You might wonder how this affects plans at Project Blue, or why Breakthrough Starshot is using infrared instead of visible-light imaging. The answer is that we have so much to learn about the Alpha Centauri system, which is Earth’s closest neighbor in space, and different imaging techniques can reveal different things.
Breakthrough Starshot plans to use ground-based telescopes imaging in thermal infrared (detecting wavelengths of 10 microns). The group will work in collaboration with the European Space Observatory to retrofit and upgrade the Very Large Telescope in Chile. Our own plan at Project Blue is to launch a small telescope the size of a washing machine into low Earth orbit and capture a direct image of Alpha Centauri using visible light. Together, these methods can help paint a more complete picture of a planet that might exist around the star.
Here’s a more detailed breakdown of relevant imaging techniques and what they can add to the scientific understanding of the Alpha Centauri system:
Imaging with ground telescopes in infrared: This direct-imaging method is the one Breakthrough Initiatives is using. It needs to be done at 10 microns (the wavelength of light at which the picture is taken) with an 8-10-meter (26 to 33 feet) ground telescope. This technique uses infrared light to help capture images of the thermal emissions that come from far-off stars and can pass through dust, gas and Earth’s atmosphere (although at a lower resolution).
This technique is a much less expensive way to capture an image than using a space-based observation. However, there are significant technological challenges, because the performance needs to exceed what’s been possible to date.
Space-based astrometry: As you can guess from its name, this method requires launching a telescope into space. The instrument measures the wobble of a star’s position in the sky caused by a planet’s presence. Although this method doesn’t produce an image, it does measure the mass and orbit of the planet. A potential Earth-like planet around Alpha Centauri is expected to be around one-half to twice the diameter of Earth.
Direct imaging with visible light: Like infrared imaging from the ground, this technique produces a direct image of the planet. Unlike infrared imaging, however, the method can provide a true-color image — think the pale blue dot image of Earth that Carl Sagan described.
Using such an image, scientists can gather information on whether a planet has an atmosphere with oxygen, along with other data complementary to infrared imaging. In some ways, visible-light imaging is easier than imaging in infrared. The image resolution is better in visible light, enabling the use of a much smaller telescope. However, there are some challenges. The brightness difference between the star and the planet is greater, for example, which requires a space telescope to distinguish between the two bodies.
Of these methods, we focused on direct imaging, because we think it can provide the most complete information about a planet’s composition. And thanks to recent technology, the cost is well within reach for a midsize space mission. Not to mention, we believe the human and emotional appeal of a visible-light photo would inspire the world and could change the course of space exploration.
Nevertheless, the Project Blue team couldn’t be more excited to see Breakthrough Initiative’s latest announcement. The discovery of Proxima b, a planet around the nearby star Proxima Centauri, led to increased interest in exploring Alpha Centauri. Similarly, researchers finding and imaging other planets in that star system will certainly spark continued interest in searching for other Earths and in developing new ways to do so.
Ultimately, researchers will use a combination of imaging tools to find and learn about nearby planets. We’re thrilled to see a project like this that could advance humanity’s understanding of its closest stellar neighbor.
An international team of scientists tasked with fleshing out the main goals of the mission, which is known as Venera-D, is wrapping up its work and will deliver its final report to NASA and the Russian Academy of Sciences’ Space Research Institute by the end of the month, said David Senske, of NASA’s Jet Propulsion Laboratory in Pasadena, California.
“Is this the mission that’s going to fly? No, but we’re getting there,” Senske, the U.S. co-chair of this “joint science-definition team,” told Space.com last month at the annual fall meeting of the American Geophysical Union, in San Francisco.
Venera-D is led by Russia, which has been developing the project for more than a decade. The mission would mark a return to once-familiar territory for the nation; Russia’s forerunner state, the Soviet Union, launched a number of probes to Venus from the early 1960s through the mid-1980s, as part of its Venera and Vega programs. (“Venera” is the Russian name for Venus.)
“Russia has always been interested in going back to Venus,” Senske said.
NASA got involved about three years ago, when Russia asked if the U.S. space agency would be interested in collaborating on the mission, Senske added.
The joint science-definition team arose out of those initial discussions. The team stood down shortly thereafter; Russia’s March 2014 annexation of Crimea prompted NASA to suspend most cooperation with Roscosmos, Russia’s federal space agency (with activities involving the International Space Station being the most prominent exception).
But the collaboration was up and running again by August 2015, Senske said, and the team met in Moscow that October. More meetings are planned, including a workshop this May that will inform decisions about the mission’s scientific instruments, he added.
Venera-D is a large-scale mission, comparable in scope to NASA “flagship” efforts such as the $2.5 billion Curiosity Mars rover, Senske said. The baseline concept calls for an orbiter that will study Venus from above for at least three years, plus a lander that will operate for a few hours on the planet’s surface.
Mission planners said they had originally hoped the lander could survive for 30 days; the “D” in Venera-D stands for “dolgozhivushaya,” which means “long lasting” in Russian. But this goal was ultimately deemed too difficult and costly, given the blistering temperatures on Venus’ surface, according to RussianSpaceWeb.com (which outlines the mission’s tortuous history in rich detail).
Data gathered by the orbiter should help scientists better understand the composition, structure and dynamics of Venus’ atmosphere, including why the planet’s air rotates so much faster than the surface does, a mysterious phenomenon known as super-rotation, Senske said.
The lander will collect further atmospheric information while descending, then study the composition and morphology of the Venusian surface after touching down.
Venera-D could incorporate additional components as well. Some ideas on the drawing board include a handful of small, relatively simple ground stations that would gather surface data for a month or so (putting the “D” back in Venera-D) and a solar-powered, uncrewed aerial vehicle that would ply the Venusian skies.
The surface of Venus is far too hot to support life as we know it, but temperatures are much more hospitable at an altitude of 31 miles (50 kilometers) or so. Furthermore, the planet’s atmosphere sports mysterious dark streaks that some astronomers have speculated might be signs of microbial life. The UAV could hypothetically investigate this possibility, sampling the air while cruising along.
Engineers have already been thinking about how to build such an aircraft. For example, the U.S. aerospace company Northrop Grumman and partner L’Garde Inc. have been researching a concept vehicle called the Venus Atmospheric Maneuverable Platform (VAMP) for several years now.
It’s still too early to know exactly what Venera-D will look like, what it will do or when the mission will launch. A liftoff in 2025 or 2026 is possible under an “aggressive” time line, Senske said. “It depends when the Russians can get this into their federal space budget,” he said.
Some things are known, however. For instance, Russia will build the orbiter and the lander, and Venera-D will launch atop Russia’s in-development Angara A5 rocket, Senske said. If NASA remains involved in the mission — which is far from a given at this point — the U.S. space agency will likely contribute smaller items, such as individual scientific instruments.
“Russia is definitely in the driver’s seat,” Senske said. “NASA is the junior partner.”
Breakthrough Initiatives, a private organization that’s dedicated to looking for life elsewhere in the universe, has enlisted the help of a massive telescope in Chile to search for planets around one of the nearest star systems to our sun, officials announced today.
Earlier this year, scientists announced the discovery of a potentially rocky planet orbiting the nearest star to the sun, Proxima Centauri; the planet orbits in a region where its surface temperature might be right to host liquid water. The discovery has created excitement about the possibility of finding more potentially habitable planets in our cosmic backyard.
Breakthrough Initiatives is hosting a program called Breakthrough Starshot, which will aim to send postage-stamp-size probes to look for planets in the Alpha Centauri system (including Proxima Centauri). As part of the new collaboration, Breakthrough Initiatives will help pay for an upgrade to an instrument on the European Southern Observatory’s (ESO) Very Large Telescope (VLT), making the instrument ideal for studying planets around Proxima Centauri and its stellar siblings.
Despite its proximity to Earth, detecting planets in the Alpha Centauri system is a challenge, primarily because the brightness of the system’s two larger stars — Alpha Centauri A and Alpha Centauri B — overwhelm the light coming from any orbiting planets, according to the statement from ESO. The new agreement between ESO and Breakthrough Initiatives will upgrade an existing instrument on the VLT, making it better equipped to search for the faint light of exoplanets.
The VLT consists of one primary 8.2-meter telescope and four auxiliary 1.2-meter telescopes, making it “the most advanced visible light telescope in the world,” according to ESO’s website. An instrument called the VISIR (VLT Imager and Spectrometer for mid-Infrared) instrument — which, as the name suggests, collects light in the midinfrared range — will get an upgrade under the new partnership. The upgraded VISIR will be equipped with a coronagraph, which is used to block out starlight. The instrument will also receive an adaptive optics system, which is used to correct for distortions of the starlight that arise in Earth’s atmosphere. In 2019, when the upgrade is scheduled to be completed, the VLT will dedicate time for a “careful search” of the Proxima Centauri system.
Founded in 2015 by entrepreneur Yuri Milner and his wife, Julia, Breakthrough Initiatives aims to “explore the Universe, seek scientific evidence of life beyond Earth, and encourage public debate from a planetary perspective.” The organization’s board consists of Yuri Milner, Facebook founder and CEO Mark Zuckerberg, and astrophysicist Stephen Hawking.
Breakthrough Initiatives currently operates three programs: Breakthrough Listen (dedicated to searching for radio signals from an intelligent alien civilization), Breakthrough Message (a competition to send a message to another intelligent civilization) and Breakthrough Starshot, which would use a massive laser accelerator to send microchip-size spacecraft to the Proxima Centauri star system.
Last year, another ambitious program that is aimed at studying planets around Proxima Centauri was announced. Titled Project Blue, the program would launch a small space telescope into orbit (eliminating the blurring effects of the Earth’s atmosphere); the telescope would be built specifically to study the Alpha Centauri A and Alpha Centauri B systems.
“Alpha Centauri” is getting the boot. The longstanding star name has been displaced by its ancient counterpart in a new International Astronomical Union (IAU) catalog that designates 227 official names for different stars in the sky.
The move was intended to reduce confusion, according to the IAU. For instance, a star like Fomalhaut has at least 30 different names, so it’s difficult to figure out what to call it — or even how to spell it. Variations over the years have included Fumalhaut, Fomalhut and even the unusual Fomal’gaut.
The IAU, which is the official arbiter of astronomical names, chose single names to refer to those stars that have historically had many. Some of the decisions may rattle longtime observers, however. For example, the binary star Alpha Centauri, which lies 4.35 light-years from the sun, is now known officially as “Rigil Kentaurus,” the ancient name for the system.
Neighboring Proxima Centauri — the closest star to the sun, at just 4.22 light-years away — will keep its name, which will make it easier to keep track of the nearest exoplanet to Earth (which is currently known by the name Proxima b.)
In many cases, the names are the same as before; for instance, while Vega is reported to have dozens of different names, “Vega” will stand as the official name, echoing the decisions of star catalogs in the Western Hemisphere for centuries. Official alphanumeric designations for stars, which are used by professional astronomers, will remain the same.
“Since the IAU is already adopting names for exoplanets and their host stars, it has been seen as necessary to catalogue the names for stars in common use from the past, and to clarify which ones will be official from now on,” Eric Mamajek, chair and organizer of the working group, said in a statement.
The decision comes after the IAU’s working group on star names began combing the literature in May 2016 to determine which star names would be officially approved. The group favored one-word names as well as those names that had histories in astronomy, culture or the natural world. (Many star names, the IAU noted, have not changed much since the Renaissance and come from Greek, Latin and Arabic roots.)
“The group aims to decide which traditional star names from cultures around the world are the official ones, in order to avoid confusion,” the IAU said in the statement. “Some of the most common names for the brightest and most famous stars in the sky had no official spelling, some stars had several names, and identical names were sometimes used for completely different stars altogether.”
The full list of the 227 stars is available on the IAU’s website. This catalog includes 18 star names that were approved in December 2015, 14 of them proposed and voted on by the public for the NameExoWorlds contest. The approved stellar names will not be available for asteroids, planetary satellites or exoplanets “so as to further reduce confusion,” the IAU said of the listing.
New observations by NASA’s Hubble Space Telescope suggest that the gas, called Smith’s Cloud, was cast from the Milky Way long ago. A new NASA video describes the cloud’s discovery in 1963 and what researchers know.
“We don’t fully understand the Smith Cloud’s origin,” Andrew Fox, an astronomer at the Space Telescope Science Institute who led the research, said in a statement from NASA. “There are two leading theories. One is that it was blown out of the Milky Way, perhaps by a cluster of supernova explosions. The other is that the Smith Cloud is an extragalactic object that has been captured by the Milky Way.” Fox’s team examined the cloud using Hubble’s Cosmic Origins Spectrograph, and saw evidence of sulfur, which absorbs ultraviolet light from the cores of three galaxies lying beyond the cloud. The team found that the amount of sulfur in Smith’s Cloud is the same as that found in the outer disk of the Milky Way, suggesting that both objects came from the same family.
“The cloud appears to have been ejected from within the Milky Way and is now falling back,” Fox said. “The cloud is fragmenting and evaporating as it plows through a halo of diffuse gas surrounding our galaxy. It’s basically falling apart.
“This means that not all of the material in Smith’s Cloud will survive to form new stars,” he added. “But if it does survive, or some part of it does, it should produce an impressive burst of star formation.”
It’s still unclear what event tore this cloud from the Milky Way’s disk and how it stayed together so long, NASA officials said in the statement. What is known, however, is that in roughly 30 million years, it will crash into our galaxy’s Perseus Arm, one of the two major spiral arms in the Milky Way. When that happens, there will be a surge of star formation when clouds of gas in the spiral arm are compressed, NASA officials said.
There are some things in the universe that you simply can’t escape. Death. Taxes. Black holes. If you time it right, you can even experience all three at once.
Black holes are made out to be uncompromising monsters, roaming the galaxies, voraciously consuming anything in their path. And their name is rightly deserved: once you fall in, once you cross the terminator line of the event horizon, you don’t come out. Not even light can escape their clutches.
But in movies, the scary monster has a weakness, and if black holes are the galactic monsters, then surely they have a vulnerability. Right?
Black holes are strange regions where gravity is strong enough to bend light, warp space and distort time.
In the 1970s, theoretical physicist Stephen Hawking made a remarkable discovery buried under the complex mathematical intersection of gravity and quantum mechanics: Black holes glow, ever so slightly, and, given enough time, they eventually dissolve.
Wow! Fantastic news! The monster can be slain! But how? How does this so-called Hawking Radiation work?
Well, general relativity is a super-complicated mathematical theory. Quantum mechanics is just as complicated. It’s a little unsatisfying to respond to “How?” with “A bunch of math,” so here’s the standard explanation: the vacuum of space is filled with virtual particles, little effervescent pairs of particles that pop into and out of existence, stealing some energy from the vacuum to exist for the briefest of moments, only to collide with each other and return to nothingness.
Every once in a while, a pair of these particles pops into existence near an event horizon, with one partner falling in and the other free to escape. Unable to collide and evaporate, the escapee goes on its merry way as a normal non-virtual particle.
Voila: The black hole appears to glow, and in doing so — in doing the work to separate a virtual particle pair and promote one of them into normal status — the black hole gives up some of its own mass. Subtly, slowly, over the eons, black holes dissolve. Not so black anymore, huh?
Here’s the thing: I don’t find that answer especially satisfying, either. For one, it has absolutely nothing to do with Hawking’s original 1974 paper, and for another, it’s just a bunch of jargon words that fill up a couple of paragraphs but don’t really go a long way to explaining this behavior. It’s not necessarily wrong, just…incomplete.
First things first: “Virtual particles” are neither virtual nor particles. In quantum field theory — our modern conception of the way particles and forces work — every kind of particle is associated with a field that permeates all of space-time. These fields aren’t just simple bookkeeping devices. They are active and alive. In fact, they’re more important than particles themselves. You can think of particles as simply excitations — or “vibrations” or “pinched-off bits,” depending on your mood — of the underlying field.
Sometimes the fields start wiggling, and those wiggles travel from one place to another. That’s what we call a “particle.” When the electron field wiggles, we get an electron. When the electromagnetic field wiggles, we get a photon. You get the idea.
Sometimes, however, those wiggles don’t really go anywhere. They fizzle out before they get to do something interesting. Space-time is full of the constantly fizzling fields.
What does this have to do with black holes? Well, when one forms, some of the fizzling quantum fields can get trapped — some permanently, appearing unfortunately within the newfound event horizon. Fields that fizzled near the event horizon end up surviving and escaping. But due to the intense gravitational time dilation near the black hole, thy appear to come out much, much later in the future.
In their complex interaction and partial entrapment with the newly forming black hole, the temporary fizzling fields get “promoted” to become normal everyday ripples — in other words, particles.
So, Hawking Radiation isn’t so much about particles opposing into existence near a present-day black hole, but the result of a complex interaction at the birth of a black hole that persists until today.
One way or the other, as far as we can tell, black holes do dissolve. I emphasize the “as far as we can tell” bit because, like I said at the beginning, generality is all sorts of hard, and quantum field theory is a beast. Put the two together and there’s bound to be some mathematical misunderstanding.
But with that caveat, we can still look at the numbers, and those numbers tell us we don’t have to worry about black holes dying anytime soon. A black hole with the mass of the sun will last a wizened 10^67 years. Considering that the current age of our universe is a paltry 13.8 times 10^9 years, that’s a good amount of time. But if you happened to turn the Eiffel Tower into a black hole, it would evaporate in only about a day. I don’t know why you would, but there you go.
A giant blob of gas and dust far off in the universe mysteriously glows bright green, and astronomers have finally figured out why. Two huge galaxies were observed in the blob’s core, and they’re surrounded by a swarm of smaller galaxies in what appears to be the birth of a massive cluster of galaxies.
Astronomers spotted the blob’s central galaxies using the Atacama Large Millimeter/submillimeter Array (ALMA) and the Very Large Telescope at the European Southern Observatory in Chile. The glowing space blob was first discovered in 2000, and the source of its light has been a mystery ever since.
One study published in 2011 suggested that polarized light emitted by the blob could have come from hidden galaxies. The new observations with ALMA and VLT allowed researchers to pinpoint two big galaxies as the sources of this light.
Further observations by the Hubble Space Telescope and the Keck Observatory in Hawaii revealed the swarm of small, faint galaxies surrounding the bigger two in the heart of the blob. Here, galaxies are forming stars at 100 times the rate of the Milky Way.
A giant green “space blob” – called the Lyman-alpha blob LAB-1 – is seen in this composite of two different images taken by the Very Large Telescope in Chile. The LAB-1 space blob is 300,000 light-years across, making it one of the largest known single objects in the universe.
Credit: ESO/M. Hayes
“For a long time, the origin of the extended Lyman-alpha light has been controversial,” Jim Geach, the study’s lead author, said in a statement. “But with the combination of new observations and cutting-edge simulations, we think we have solved a 15-year-old mystery.”
So-called “Lyman-alpha blobs” are some of the biggest things in space. This particular space blob, named SSA22-Lyman-alpha Blob 1 (LAB-1), is the largest of its kind. It measures about 300,000 light-years across, or three times the size of the Milky Way galaxy.
LAB-1 is located 11.5 billion light-years from Earth, so the light we observe from it is almost as old as the universe (13.8 billion years). This means that looking at LAB-1 provides a window into the early history of the universe.
Lyman-alpha blobs consist mainly of hydrogen gas and emit a particular wavelength of ultraviolet light called Lyman-alpha radiation. The light looks green to viewers on Earth, because its wavelength is stretched by the expanding universe during its long trip here.
This is a snapshot from a computer simulation of the evolution of a Lyman-alpha Blob similar to LAB-1. Gas within the dark matter halo is color- coded so that cold gas (mainly hydrogen) appears red and hot gas appears white. At the center of this system are two star-forming galaxies surrounded by hot gas and many smaller satellite galaxies that appear as small red clumps.
Once they had observed the sources of light from within the blob, the researchers created simulations of galaxy formation using NASA’s Pleiades supercomputer. They wanted to show that ultraviolet light — a byproduct of star formation — scatters off hydrogen gas to create a bright, glowing mega-blob like LAB-1.
“Think of a streetlight on a foggy night — you see the diffuse glow because light is scattering off the tiny water droplets,” Geach said in the same statement. “A similar thing is happening here, except the streetlight is an intensely star-forming galaxy and the fog is a huge cloud of intergalactic gas. The galaxies are illuminating their surroundings.”
The simulations also track gas and dark matter in the blob as it evolves into a galaxy. “Lyman-alpha Blob-1 is the site of formation of a massive elliptical galaxy that will one day be the heart of a giant cluster,” Geach added
Monster black holes can be millions of times more massive than the sun. If a star happens to wander too close, the black hole’s extreme gravitational forces can tear the star into shreds, in an event called “stellar tidal disruption.”
This kind of stellar destruction may also spit out a bright flare of energy in the form of ultraviolet and X-ray light. The two new studies examine how surrounding dust absorbs and re-emits the light from those flares, like a cosmic echo, according to a statement from NASA’s Jet Propulsion Laboratory (JPL).
“This is the first time we have clearly seen the infrared-light echoes from multiple tidal disruption events,” Sjoert van Velzen, a postdoctoral fellow at Johns Hopkins University and lead author of one study, said in the statement.
The new studies use data from NASA’s Wide-field Infrared Survey Explorer (WISE). The NASA study led by van Velzen used these “echoes” to identify three black holes in the act of devouring stars. The second study, led by Ning Jiang, a postdoctoral researcher at the University of Science and Technology of China, identified a potential fourth light echo.
Flares emitted from stellar tidal disruptions are extremely energetic and “destroy any dust” that is within the immediate neighborhood, according to NASA. However, a patchy, spherical web of dust that resides a few trillion miles (half a light-year) from the black hole can survive the flare and absorb light released from the star being gobbled up
“The black hole has destroyed everything between itself and this dust shell,” van Velzen said in the statement. “It’s as though the black hole has cleaned its room by throwing flames.”
The absorbed light heats the more distant dust, which in turn gives off infrared radiation that the WISE instrument can measure. These emissions can be detected for up to a year after the flare is at its brightest, the statement said. Scientists are able to characterize and locate the dust by measuring the delay between the original light flare and the subsequent echoes, according to the NASA study, which will be published in the Astrophysical Journal.
“Our study confirms that the dust is there, and that we can use it to determine how much energy was generated in the destruction of the star,” Varoujan Gorjian, an astronomer at JPL and co-author of the paper led by van Velzen, said in the statement.