Discovering life was not on the agenda when Cassini was designed and launched two decades ago. Its instruments can’t capture microbes or detect life, but in a couple of dozen passes through the plumes of Enceladus, it has detected various molecules associated with life: water vapor, carbon dioxide, methane, molecular nitrogen, propane, acetylene, formaldehyde and traces of ammonia.
Wednesday’s dive will be the deepest Cassini will make through the plumes, only 30 miles above the icy surface. Scientists are especially interested in measuring the amount of hydrogen gas in the plume, which would tell them how much energy and heat are being generated by chemical reactions in hydrothermal vents at the bottom of the moon’s ocean.
That’s pretty crazy…it sounds like science fiction. NASA is doing a wonderful job producing great science with the lean budgets they are given.
Jason Wright, an astronomer from Penn State University, is set to publish an alternative interpretation of the light pattern. SETI researchers have long suggested that we might be able to detect distant extraterrestrial civilizations, by looking for enormous technological artifacts orbiting other stars. Wright and his co-authors say the unusual star’s light pattern is consistent with a “swarm of megastructures,” perhaps stellar-light collectors, technology designed to catch energy from the star.
“When [Boyajian] showed me the data, I was fascinated by how crazy it looked,” Wright told me. “Aliens should always be the very last hypothesis you consider, but this looked like something you would expect an alien civilization to build.”
Boyajian is now working with Wright and Andrew Siemion, the Director of the SETI Research Center at the University of California, Berkeley. The three of them are writing up a proposal. They want to point a massive radio dish at the unusual star, to see if it emits radio waves at frequencies associated with technological activity.
Artist and programmer Jeff Thompson has compiled 15,000 hand-drawn maps of the Sun made by astronomers into a single video, creating a mesmerizing and delightfully makeshift stop-motion animation of the Sun’s activity over the last 43 years. Astronomers have been drawing these “solar synoptic maps” since 1956 in order to keep track of the Sun’s “weather”…sunspots, flares, and the like. (via slate)
“If you look at encrypted communication, if they are properly encrypted, there is no real way to tell that they are encrypted,” Snowden said. “You can’t distinguish a properly encrypted communication from random behaviour.”
Therefore, Snowden continued, as human and alien societies get more sophisticated and move from “open communications” to encrypted communication, the signals being broadcast will quickly stop looking like recognisable signals.
“So if you have an an alien civilization trying to listen for other civilizations,” he said, “or our civilization trying to listen for aliens, there’s only one small period in the development of their society when all their communication will be sent via the most primitive and most unprotected means.”
After that, Snowden said, alien messages would be so encrypted that it would render them unrecognisable, “indistinguishable to us from cosmic microwave background radiation”. In that case, humanity would not even realise it had received such communications.
Snowden shared his hypothesis with Neil deGrasse Tyson on Tyson’s podcast, StarTalk.
A pair of filmmakers, Wylie Overstreet and Alex Gorosh, built a scale model of the solar system in the Nevada desert and made a time lapse of the result. For orbits, they drove their car in circles around “the Sun”. The Earth they used was the size of a marble, which made Neptune’s orbit seven miles across. (via the kid should see this)
The backlit photos of Pluto just posted by NASA are breathtaking. Look at this:
Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA’s New Horizons spacecraft looked back toward the sun and captured this near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto’s horizon. The smooth expanse of the informally named Sputnik Planum (right) is flanked to the west (left) by rugged mountains up to 11,000 feet (3,500 meters) high, including the informally named Norgay Montes in the foreground and Hillary Montes on the skyline. The backlighting highlights more than a dozen layers of haze in Pluto’s tenuous but distended atmosphere. The image was taken from a distance of 11,000 miles (18,000 kilometers) to Pluto; the scene is 230 miles (380 kilometers) across.
As they say, best viewed large. Some of those features don’t look like mountains at all, but like reptile scales or huge shards of ice pushed up into the sky. Fantastic.
Bjorn Jonsson used the photos taken by NASA’s New Horizons spacecraft to make an animation of the probe’s flyby of Pluto.
The time covered is 09:35 to 13:35 (closest approach occurred near 11:50). Pluto’s atmosphere is included and should be fairly realistic from about 10 seconds into the animation and to the end. Earlier it is largely just guesswork that can be improved in the future once all data has been downlinked from the spacecraft. Light from Pluto’s satellite Charon illuminates Pluto’s night side but is exaggerated here, in reality it would be only barely visible or not visible at all.
Fantastic…and Pluto’s moons flying about in the background is the cherry on the top. (via @BadAstronomer)
This image was tweeted out by the NASA Europa Mission account the other day:
One of these images is of Europa, Jupiter’s icy moon, and the other eight are frying pans. Can you pick Europa out? Hint: frying pans tend not to have impact craters.
Update: The photos of the frying pans were taken by Christopher Jonassen, whose work I featured back in 2011 (which I had totally forgotten about). At the time, I even joked about the pans looking like a Jovian moon. kottke.org is a flat circle. (thx, tony)
How massive are they? The Sun is 1 solar mass and as wide as 109 Earths. Sagittarius A, the black hole at the center of the Milky Way, weighs 4.3 million solar masses and is as wide as Mercury is far from the Sun. The black hole at the center of the Phoenix Cluster is one of the largest known black holes in the Universe; it’s 73 billion miles across, which is 19 times larger than our entire solar system (from the Sun to Pluto). As for how much it weighs, check this out:
I also like that if you made the Earth into a black hole, it would be the size of a peanut. (thx, reidar)
Emily Lakdawalla provides an update on all of the exploration that’s going on in our solar system this month. Here’s a quick map view of the 20+ spacecraft exploring our solar system beyond Earth:
Mars remains the most active spot beyond Earth in the solar system. This week, Mars Reconnaissance Orbiter reaches its 10th anniversary of service in space, but it’s far from the oldest spacecraft in orbit at Mars; Mars Express and Mars Odyssey are still at work up there. Mars Orbiter Mission has ventured into an extended mission and is still returning photos, though apparently none of the full-disk images in a variety of phases that I had hoped for from its 4-Megapixel color camera. Even Mars’ newest resident, MAVEN, is three-quarters of the way through its one-year primary science mission, which began on November 16, 2014. MAVEN’s mission will undoubtedly be extended long beyond that, as it will be needed to support surface missions if and when Odyssey and Mars Reconnaissance Orbiter eventually fail.
Both Opportunity and Curiosity have been very active lately. Opportunity has finally reached Marathon Valley, a site identified from orbit to have signs of clay chemistry. The team is excited about the science prospects even though the rover’s memory problems persist.
This morning, the New Horizons probe zinged safely1 past Pluto. Before it did, it transmitted the best photo we’ve seen of Pluto so far…the last one we’ll get before we get the really good stuff. Look at this:
The probe’s “I’m OK!” message will reach Earth around 9pm ET tonight and we’ll start seeing photos from the flyby Wednesday afternoon…there’s a NASA press conference scheduled for 3pm ET on July 15. So exciting!
Update: The photo above is also the best full-disk image of Pluto that we will get…the rest will be close-ups and such. So that’s the official Pluto portrait from now on, folks.
Well, hopefully. The probe is due to transmit a “I’m OK!” message back to Earth later today (at around 9pm ET). *fingers crossed*↩
As the New Horizons probe nears Pluto, I’ve been reading a bit more about how it’s going to work and what sort of photos we’re going to get. Emily Lakdawalla has a comprehensive post about what to expect when you’re expecting a flyby of Pluto. The post contains an image of approximations of the photos New Horizon will take, using Voyager images of Jovian and Saturnian moons as stand-ins. The highest resolution photo of Pluto will be 0.4 km/pixel…it’ll have this approximate level of detail:
Which is pretty amazing and exciting considering that before the mission started this was our best view of Pluto:
NASA’s Eyes app lets you see a simulation of the probe as it approaches Pluto, but if you don’t want to download anything, you can watch this video of the flyby instead:
I had no idea the probe spun around so much as it grabs photos & scans and then beams them back to Earth. And the flyby is so fast! New Horizons is currently moving at 32,500 mph relative to the Sun…it’s travelling just over 9 miles every second. (via @Tim_Meyer_ & @badastronomer)
New Horizons will reach its closest approach to Pluto in just under 6 days, on July 14. The probe will pass within 7,800 miles of the surface…I can’t wait to find out what that day’s photos look like.
Update: You don’t even need to wait until tomorrow for that better image…here’s one that NASA released just a short while ago. Tune in tomorrow for an even better view.
New Horizons’ imaging capability of Pluto surpassed Hubble’s on May 15, 2015. So every picture since then has been better than what we’ve had previously.↩
“If the Milky Way is a sea of stars, then these newly discovered galaxies are like wisps of clouds”, said van Dokkum. “We are beginning to form some ideas about how they were born and it’s remarkable they have survived at all. They are found in a dense, violent region of space filled with dark matter and galaxies whizzing around, so we think they must be cloaked in their own invisible dark matter ‘shields’ that are protecting them from this intergalactic assault.”
The night sky in such galaxies would look a lot like our skies do in large cities:
“If there are any aliens living on a planet in an ultra-diffuse galaxy, they would have no band of light across the sky, like our own Milky Way, to tell them they were living in a galaxy. The night sky would be much emptier of stars,” said team member Aaron Romanowsky, of San Jose State University.
A group of astronomy enthusiasts rented a plane and flew through the shadow cast by the recent eclipse of the Sun. One passenger took the following video. Look at that shadow creeping across the cloud cover! So cool.
Ok, Pluto fans. They evicted Pluto from our solar system’s planetary pantheon, but a NASA mission launched in 2006 is nearing the dwarf planet with its cameras. We’ll soon have photos of Pluto that are much more high resolution than we currently have, which means scientists will need names for all the new geographic features. The Our Pluto site has been set up to help suggest and vote on names for these features. Naming themes include historic explorers, travelers to the underworld, and scientists and engineers. Go vote! (via slate)
Two teams of NASA scientists have discovered evidence that hydrothermal vents on the Saturnian moon of Enceladus show signs of “active hot-water chemistry”. Why is that exciting? Because similar chemistry occurs deep in the Earth’s oceans *and* can support life. Phil Plait explains.
We see these vents in the ocean bottom on Earth, too. The water there is very hot, heated by tectonic processes inside Earth’s crust. It brings up minerals and nutrients, and life thrives there. A lot of the processes are the same as what’s imagined is happening on Enceladus; minerals are dissolved in hot water that spews up into the cold ocean, precipitating out. A lot of it is sulfur based, but amazingly life exists there anyway. The environment is highly toxic to humans-huge pressure, boiling water near the vents, freezing a bit farther away, and loaded with icky chemicals-but as a scientist once said, “Life finds a way.”
Between the evidence of past flowing water on Mars, Titan’s hydrocarbon lakes, Europa’s underground ocean, and Enceladus, it seems increasingly probable we’ll find life somewhere else in the solar system. That’s a pretty exciting prospect! (via @ericholthaus)
Update: It was also announced today that the Hubble has detected signs of a salty underground ocean on Jupiter’s moon Ganymede.
New observations of the moon using Hubble support this. Ganymede has a weak magnetic field, and, like on Earth, this generates an aurora-the glow created when high-speed subatomic particles slam into the extremely thin atmosphere. This glow is brightest in ultraviolet, and so astronomers used the Space Telescope Imaging Spectrograph (my old camera!) on Hubble to observe Ganymede. STIS is quite sensitive to UV and detected the aurora.
Now this part is a bit tricky: Jupiter has a powerful magnetic field as well, which interacts with Ganymede’s. As they do, the aurora changes position over time, moving up and down in latitude. However, the observations show that the aurorae do not change nearly as much as expected if Ganymede were solid. The best way to explain this is if the moon has a salty ocean under its surface. The ocean would have its own magnetic field and would resist the influence of Jupiter’s magnetic field, which in turn keeps the aurora steadier.
Turns out there’s water all over the place in the solar system. How about that?
Supernovas are among the most violent and rare events in the universe, occurring perhaps once per century in a typical galaxy. They outshine entire galaxies, spewing elemental particles like oxygen and gold out into space to form the foundations of new worlds, and leaving behind crushed remnants called neutron stars or black holes.
Because of the galaxy cluster standing between this star and the Hubble, “basically, we got to see the supernova four times,” Dr. Kelly said. And the explosion is expected to appear again in another part of the sky in the next 10 years. Timing the delays between its appearances, he explained, will allow astronomers to refine measurements of how fast the universe is expanding and to map the mysterious dark matter that supplies the bulk of the mass and gravitational oomph of the universe.
Scientists expect the supernova to reappear in the next few years. Gravitational lensing was predicted by Einstein’s general theory of relativity and as Overbye writes, “the heavens continue to light candles for Albert Einstein.”
For Scientific American, Jen Christiansen tracks down where the iconic image on the cover of Joy Division’s Unknown Pleasures came from. Designer Peter Saville found the image, a stacked graph of successive radio signals from pulsar CP 1919, in a 1977 astronomy encyclopedia but it actually originated in a 1970 Ph.D. thesis.
By now I had also combed through early discovery articles in scientific journals and every book anthology on pulsars I could get my hands on to learn more about early pulsar visualizations. The more I learned, the more this descriptor in the 1971 Ostriker caption began to feel significant; “computer-generated illustration.” The charts from Bell at Mullard were output in real time, using analogue plotting tools. A transition in technology from analogue to digital seemed to have been taking place between the discovery of pulsars in 1967 to the work being conducting at Arecibo in 1968 through the early 1970’s. A cohort of doctoral students from Cornell University seemed to be embracing that shift, working on the cutting edge of digital analysis and pulsar data output. One PhD thesis title from that group in particular caught my attention, “Radio Observations of the Pulse Profiles and Dispersion Measures of Twelve Pulsars,” by Harold D. Craft, Jr. (September 1970).
When a star gets old and fat, it explodes in a supernova, leaving a neutron star in its wake. Neutron stars are heavily magnetized and incredibly dense, approximately two times the mass of the Sun packed into an area the size of the borough of Queens. That’s right around the density of an atomic nucleus, which isn’t surprising given that neutron stars are mostly composed of neutrons. A teaspoon of neutron star would weigh billions of tons.
A pulsar is a neutron star that quickly rotates. As the star spins, electromagnetic beams are shot out of the magnetic poles, which sweep around in space like a lighthouse light. Pulsars can spin anywhere from once every few seconds to 700 times/second, with the surface speed approaching 1/4 of the speed of light. These successive waves of electromagnetic pulses, arriving every 1.34 seconds, are what’s depicted in the stacked graph. Metaphorical meanings of its placement on the cover of a Joy Division record are left as an exercise to the reader.
Nothing is faster than the speed of light. But compared to the unimaginable size of the Universe, light is actually extremely slow. This video is 45 minutes long and during that time, a photon emitted from the Sun1 will only travel through a portion of our solar system.
In our terrestrial view of things, the speed of light seems incredibly fast. But as soon as you view it against the vast distances of the universe, it’s unfortunately very slow. This animation illustrates, in realtime, the journey of a photon of light emitted from the sun and traveling across a portion of the solar system.
It takes light more than 43 minutes to travel to Jupiter and even to travel the diameter of the Sun takes 4.6 seconds. (thx, andy)
To even fight its way out of the Sun is an incredible journey for a photon. The Sun is so dense that a photon generated at the core is absorbed and re-emitted trillions of times by hydrogen nuclei on its way out. By some estimates, it may take up to 40,000 years for a photon to escape the Sun’s surface and head on out to the cold reaches of space.↩
This is an ultra-HD time lapse of planet Earth in infrared. Infrared light is absorbed by clouds and water vapor, so the result is a sphere of roiling storms and trade winds.
From the Russian Space Agency, a video of what the sky would look like if the Sun were replaced by some other stars. It starts off with the binary star system of Alpha Centuri, but watch until the end for Polaris, which has a radius 46 times that of the Sun.
The Hubble Space Telescope was launched 25 years ago, and to start the celebration, NASA has released a pair of images that actually did make this space nerd’s jaw drop. The first is an update of a classic: a much sharper photo of the so-called Pillars of Creation:
Although NASA’s Hubble Space Telescope has taken many breathtaking images of the universe, one snapshot stands out from the rest: the iconic view of the so-called “Pillars of Creation.” The jaw-dropping photo, taken in 1995, revealed never-before-seen details of three giant columns of cold gas bathed in the scorching ultraviolet light from a cluster of young, massive stars in a small region of the Eagle Nebula, or M16.
The second image isn’t so immediately amazing but is my favorite of the two. It’s a photo of half of the Andromeda galaxy, the big galaxy closest to our own in distance but also in rough size and shape. Here’s a very very scaled-down version of it:
The largest NASA Hubble Space Telescope image ever assembled, this sweeping view of a portion of the Andromeda galaxy (M31) is the sharpest large composite image ever taken of our galactic neighbor. Though the galaxy is over 2 million light-years away, the Hubble telescope is powerful enough to resolve individual stars in a 61,000-light-year-long section of the galaxy’s pancake-shaped disk. It’s like photographing a beach and resolving individual grains of sand. And, there are lots of stars in this sweeping view — over 100 million, with some of them in thousands of star clusters seen embedded in the disk.
The original image is 1500 megapixels (1.5 gigapixels!), which is so big that you’d need 600 HD televisions to display the whole thing. But if you take the biggest reasonable size available for download (100 megapixels) and zoom in on it, you get this:
That looks like JPEG compression noise, right? Nope, each one of those dots is a star…some of the 100 million individual stars that can be seen in the full image.
That’s right, Keanu. Whoa. For an even closer look, check out this annotated close-up released by NASA:
As you stroll from one to another, you can’t help noticing that the first four planets are really close together. It takes a few seconds, a few tens of steps, to walk from the Sun to Mercury and then on to Venus, Earth and Mars. By contrast, Jupiter is a full two-minute walk down the block, just past Moosewood Restaurant, waiting for someone to stop by and admire it. The remaining planets are even lonelier, each marooned in its own part of town. The whole walk, from the Sun to Pluto, is about three-quarters of a mile long and takes about 15 minutes.
My favorite detail: they added a new station to the Sagan Walk, the star nearest to our solar system. It’s in Hawaii.
This is a time lapse of the surface of the Sun, constructed of more than 17,000 images taken by the Solar Dynamics Observatory from Oct 14 to Oct 30, 2014. The bright area that starts on the far right is sunspot AR 12192, the largest observed sunspot since 1990.
The sunspot is about 80,000 miles across (as wide as 10 Earths) and it’s visible from Earth with the naked eye. Best viewed as large as possible…I bet this looks amazing on the new retina iMac. (via @pageman)
And here’s a neutron star nestled next to Liverpool on the northwest coast of England:
A neutron star also crams in over 1.5 times the mass of the Sun into a tiny ball maybe not much bigger than your daily commute to work, and the Sun is huge (see the size of the Sun later). So this thing is incredibly dense, so dense in fact that just a tea spoon of it would weigh over a billion tonnes, and if you could stand on its surface you’d feel the gravitational pull of 200 billion times that of our planet…not that you’d ever survive it of course.
From Michael Benson comes Cosmigraphics, a survey of many ways in which humans have represented the Universe, from antiquity on up to the present day.
Selecting artful and profound illustrations and maps, many hidden away in the world’s great science libraries and virtually unknown today, he chronicles more than 1,000 years of humanity’s ever-expanding understanding of the size and shape of space itself. He shows how the invention of the telescope inspired visions of unimaginably distant places and explains why today we turn to supercomputer simulations to reveal deeper truths about space-time.
Among the narrative threads woven into the book are the 18th-century visual meditations on the possible design of the Milky Way - including the astonishing work of the undeservedly obscure English astronomer Thomas Wright, who in 1750 reasoned his way to (and illustrated) the flattened-disk form of our galaxy. In a book stuffed with exquisite mezzotint plates, Wright also conceived of another revolutionary concept: a multigalaxy cosmos. All of this a quarter-century before the American Revolution, at a time when the Milky Way was thought to constitute the entirety of the universe.
Stay Connected