kottke.org posts about astronomy
A comet called Comet C/2022 E3 (ZTF) is currently visible in northern skies with the naked eye and here’s how you can catch a glimpse for yourself.
Comet C/2022 E3 (ZTF) is currently making its way through the northern skies and should reach its brightest magnitude in early February, according to In-The-Sky.org as it approaches perigee on Feb. 1. To see the comet for yourself, look to the north just after sunset and look for a faint greenish glow. Under the right dark sky conditions, the comet could be visible to the unaided eye, but binoculars will certainly make the job easier.
The comet last visited the Earth about 50,000 years ago and this may be its last visit before it leaves the solar system for good. The unusual green color results from a rare chemical reaction:
The comet itself isn’t green, but its head does appear to glow green thanks to a somewhat rare chemical reaction. The glow likely comes from diatomic carbon (C2) — a simple molecule made of two carbon atoms bonded together. When ultraviolet light from the sun breaks this molecule down, it emits a greenish glow that can last for several days, according to a 2021 study in the journal Proceedings of the National Academy of Sciences.
This eerie light disappears before making its way to the comet’s tail, or coma, which is made of gas. That gas is once again a result of solar radiation - in this case, sunlight causes part of the comet to sublimate, or transition from a solid into a gas without entering a liquid state. That gas streaks behind the comet, often glowing blue from the ultraviolet light.
The best, brightest views of the comet will be right around Feb 1, when it will be near the constellation Camelopardalis (almost due north, in the general vicinity of the Big and Little Dippers) right after sunset — use an app like Sky Guide to help find it. It’s cloudy here in Vermont until Friday…I’m going to try to catch a glimpse of it then.
Amazing photo of Comet C/2022 E3 (ZTF) above by Dan Bartlett.
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South Korea currently has a probe called Danuri orbiting the Moon at an altitude of about 62 miles above the surface. It’s just begun its mission but has already sent back some black & white photos of the Moon and the Earth, including the two above. Over at EarthSky, Dave Adalian says these shots “rival the work of legendary nature photographer Ansel Adams” and it’s difficult to disagree.
Also worth a look: Danuri’s shot of the Earth and Moon from a distance, hanging in the blackness of space like a pair of pearls. (via petapixel)
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Sure, the James Webb Space Telescope and ok, the Hubble, but the Solar Dynamics Observatory has to be right up there for producing some of the most jaw-dropping space photography around. This 4K video from NASA’s Goddard Space Flight Center condenses 133 days of the SRO’s observations of the Sun into a soothing hour-long time lapse.
See also The Highest Resolution Photo of the Sun Ever Taken, A Decade of Sun, Epic Time Lapse Videos of Mercury’s Transit of the Sun, and Thermonuclear Art.
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On July 15, 1965, NASA’s Mariner 4 probe flew within 6,118 miles of the surface of Mars, capturing images as it passed over the planet. The image data was transmitted back to scientists on Earth, but they didn’t have a good way to quickly render a photograph from it. They determined that the fastest way to see what Mariner 4 had seen was to print out the imaging data as a series of numbers, paste them into a grid, buy a set of pastels from a nearby art store, and do a paint-by-numbers job with the pastels on the data grid. The result (pictured above) was the first closeup representation of the surface of an extraterrestrial planet — in color, no less!
After the flyby of the planet it would take several hours for computers to process a real image. So while they were waiting, the engineers thought of different ways of taking the 1’s and 0’s from the actual data and create an image. After a few variations, it seemed most efficient to print out the digits and color over them based upon how bright each pixel was. So Mr. Grumm went to a local art store and asked for a set of chalk with different shades of gray. The art store replied that they “did not sell chalk” (as that was apparently too low for them, only convenience stores sold “chalk”), but they did have colored pastels. Richard did not want to spend a lot of time arguing with them, so he bought the pastels (actual pastels seen below), had the 1’s and 0’s printed out on ticker tape about 3in wide, and his team colored them by their brightness level (color key seen below).
Here’s a closer view of the pastels and numbers:
The choice of color palette was serendipitous:
Though he used a brown/red color scheme, the thought that Mars was red did not enter his mind. He really was looking for the colors that best represented a grey scale, since that was what they were going to get anyway. It is uncanny how close his color scheme is to the actual colors of Mars. It’s as if they came right out of current images of the planet.
Compare with the photography we’re getting from Curiosity these days; we’ve come a long way in the last 60 years. (via @jenniferrrrrroberts and robin sloan)
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Over the weekend, NASA’s Artemis I mission returned from a 25-day trip to the Moon. The mission was a test-run of the rockets, systems, and spacecraft that will return humans to the surface of the Moon. Visual imaging has been an integral part of even the earliest space missions — strap a camera to a spacecraft, let the people see what space looks like, and they will be inspired. Well, the photographs returned by Artemis I’s Orion spacecraft have certainly been inspirational. Working from NASA’s archive of images (on Flickr too), I’ve selected some of the most interesting and dramatic photos from the mission. The one at the top, showing a crescent Earth rising over the Moon’s surface, might be one of my favorite space photos ever (and that’s really saying something) — you can see a bigger version of it here.
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Science fiction and fantasy artists could labor for a thousand years and never come up with something as beautiful and unbelievable as the aurora borealis. Nature: still undefeated. Those two shots are from the 2022 Northern Lights Photographer of the Year awards — the top one was captured by Tor-Ivar Næss in Norway and the bottom one was taken in Denmark by Ruslan Merzlyakov.
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This 360° time lapse video, filmed by meteorologist Witek Kaszkin in 2015, follows the never-setting Sun in a 24-hour trip around the sky above the Arctic Circle as the icy Arctic landscape is bathed in constant summer sunlight.
See also — and I may be burying the lede here — Kaszkin’s video of a total solar eclipse filmed from the same location. Wow. (via the kid should see this)
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On the 26th flight of Ingenuity, NASA’s helicopter on Mars, it spotted and photographed the wreckage of the Perseverance rover’s landing gear, protective shell, and parachute. From a NY Times article on the photos:
“There’s definitely a sci-fi element to it,” Ian Clark, an engineer who worked on Perseverance’s parachute system, said of photographs released on Wednesday. “It exudes otherworldly, doesn’t it?”
Part of the reason NASA had Ingenuity go take a look is to see how all of that equipment held up during the landing process. Data from the photos will inform future missions.
“Perseverance had the best-documented Mars landing in history, with cameras showing everything from parachute inflation to touchdown,” said JPL’s Ian Clark, former Perseverance systems engineer and now Mars Sample Return ascent phase lead. “But Ingenuity’s images offer a different vantage point. If they either reinforce that our systems worked as we think they worked or provide even one dataset of engineering information we can use for Mars Sample Return planning, it will be amazing. And if not, the pictures are still phenomenal and inspiring.”
In the images of the upright backshell and the debris field that resulted from it impacting the surface at about 78 mph (126 kph), the backshell’s protective coating appears to have remained intact during Mars atmospheric entry. Many of the 80 high-strength suspension lines connecting the backshell to the parachute are visible and also appear intact. Spread out and covered in dust, only about a third of the orange-and-white parachute — at 70.5 feet (21.5 meters) wide, it was the biggest ever deployed on Mars — can be seen, but the canopy shows no signs of damage from the supersonic airflow during inflation. Several weeks of analysis will be needed for a more final verdict.
It is really remarkable, the images we’re seeing from Mars, taken by a robotic helicopter.
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Wow, NASA just released a video shot by the Mars Perseverance rover of a solar eclipse by the moon Phobos. The video description calls it “the most zoomed-in, highest frame-rate observation of a Phobos solar eclipse ever taken from the Martian surface”. According to this article from JPL, the video of the eclipse is played in realtime; it only lasted about 40 seconds.
Captured with Perseverance’s next-generation Mastcam-Z camera on April 2, the 397th Martian day, or sol, of the mission, the eclipse lasted a little over 40 seconds — much shorter than a typical solar eclipse involving Earth’s Moon. (Phobos is about 157 times smaller than Earth’s Moon. Mars’ other moon, Deimos, is even smaller.)
Just a hunk of space rock passing in front of a massive burning ball of gas recorded by a robot from the surface of an extraterrestrial planet, no big deal.
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Seán Doran strikes again. In this short flyover rendered in 8K resolution by Doran, we’re treated to a detailed look at a crater on Mars. The imagery is from the HiRISE camera onboard the Mars Reconnaissance Orbiter. Beautiful — worth taking a second or third pass to catch all the details.
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The European Space Agency’s Solar Orbiter recently took 25 images of the Sun from a distance of 46 million miles that, when stitched all together, form the highest resolution photo of the Sun (and its corona) ever created.
The high-resolution telescope of EUI takes pictures of such high spatial resolution that, at that close distance, a mosaic of 25 individual images is needed to cover the entire Sun. Taken one after the other, the full image was captured over a period of more than four hours because each tile takes about 10 minutes, including the time for the spacecraft to point from one segment to the next.
In total, the final image contains more than 83 million pixels in a 9148 x 9112 pixel grid. For comparison, this image has a resolution that is ten times better than what a 4K TV screen can display.
You can zoom in on the image here to see how remarkably detailed it is.
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Within the past 100 million years, an icy moon got too close to Saturn and the planet’s gravity ripped it apart, forming the iconic rings. This clip from BBC’s The Planets details how that happened, accompanied by some amazing photography from NASA’s Cassini mission.
I got this from The Kid Should See This, who shared some ring facts:
They are younger than the dinosaurs, they form a disk wider than Jupiter that averages just 9 meters (30 feet) thick, and thanks to Cassini, we now know that there are tall peaks rising as high as 2.5 kilometers (1.6 miles) from the planet’s B ring.
I’ve shared this story on the site before, but seeing the rings of Saturn through my telescope in my backyard as a teenager made a massive impression on me as to the scale of the solar system and humankind’s ability to understand it through science and technology. I still can’t believe you can see those rings with a cheap telescope or binoculars. Incredible.
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No doubt motivated by this month’s release of Moonfall, the latest movie from disaster shlockmeister Roland Emmerich, Kurzgesagt has made a video that shows what would happen to civilization should the Moon somehow get knocked from its orbit and head straight for the Earth. Spoiler: the Moon doesn’t even need to reach us to kill almost all life on the planet.
See also A Scientific Simulation of Seveneves’ Moon Disaster.
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The James Webb Space Telescope is designed to be positioned near one of the five Lagrange Points in the Sun/Earth system, special areas of gravitational equilibrium that keep objects stationary relative to both the Earth and the Sun. Here’s how Lagrange Points work and why they are so useful for spacecraft like the Webb.
See also What Makes Lagrange Points Special Locations In Space.
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Space is mostly just what it says on the tin: empty space. The solar system is no exception; it’s a massive volume occupied by little more than the Sun’s mass — the mass of all the planets, moons, comets, asteroids, space dust, and stray electrons are just a bit more than a rounding error. But oh what mass it is when you get up close to it.
The NASA space probe Cassini, on its seven-year journey to Saturn, cozied up to Jupiter in December 2000 and captured a succession of images of Io and Europa passing over the Great Red Spot during the moons’ orbit of the gas giant planet. Kevin Gill turned those images into the incredible video embedded above. That we have such crisp, smooth video of two small moons orbiting a planet some 444 million miles away from Earth is something of a miracle — it looks totally rendered. Also in the video is footage of Titan orbiting Saturn — that horizontal line bisecting the frame is Saturn’s rings, edge-on.
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The James Webb Space Telescope is still winging its way to its permanent home at the L2 point1 about 930,000 miles from Earth — it’s due to arrive in about 4 days. It’s a massive and fascinating project and for his YouTube series Smarter Every Day, Destin Sandlin talked to Nobel laureate John Mather, the senior project scientist for the JWST, about how the telescope works.
Also worth a watch is Real Engineering’s The Insane Engineering of James Webb Telescope:
It really is a marvel of modern science & engineering — I can’t wait to see what the telescope sees once it’s fully operational.
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Charles and Ray Eames’ 1977 short film Powers of Ten is one of the best bits of science communication ever created…and a personal favorite of mine. Here’s a description of the original film:
Powers of Ten takes us on an adventure in magnitudes. Starting at a picnic by the lakeside in Chicago, this famous film transports us to the outer edges of the universe. Every ten seconds we view the starting point from ten times farther out until our own galaxy is visible only a s a speck of light among many others. Returning to Earth with breathtaking speed, we move inward — into the hand of the sleeping picnicker — with ten times more magnification every ten seconds. Our journey ends inside a proton of a carbon atom within a DNA molecule in a white blood cell.
As an homage, the BBC and particle physicist Brian Cox have created an updated version that reflects what we’ve learned about the universe in the 45 years since Powers of Ten was made. The new video zooms out to the limits of our current observational powers, to about 100 billion light years away, 1000X wider than in the original. (I wish they would have done the zoom in part of the video too, but maybe next year!)
And if you’d like to explore the scales of the universe for yourself, check out the Universe in a Nutshell app from Tim Urban and Kurzgesagt — you can zoom in and out as far as you want and interact with and learn about objects along the way.
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Using a composite of 25 different shots done over a period of 12 minutes in his backyard, amateur astrophotographer Andrew McCarthy created this stunning image of Comet Leonard. From PetaPixel:
Processing comet images is a challenge because even in the span of 12 minutes, the comet drifts across the frame relative to the background stars,” McCarthy tells PetaPixel. “Due to the comet’s motion, it has to be stacked differently. I tell the software to stack the images based on the comet position and star positions separately, which is then combined together to produce an image with the comet and stars both sharp.
See also this image of Leonard and McCarthy’s colorful photo of a full moon.
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Check out some of the best aurora borealis and aurora australis photos taken in 2021 in the results of the 2021 Northern Lights Photographer of the Year competition.1 My three favorites (embedded above) were taken by Larryn Rae, Marc Adamus, and Frøydis Dalheim. (thx, caroline)
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In this entertaining, informative, and charmingly goofy video, Dr. Kevin Hainline tells us all about the James Webb Space Telescope. The JWST is a bigger and better version of the Hubble Space Telescope and will allow scientists to peer deeper into the universe and farther back in time than ever before.
Listen, science is hard! Engineering is hard! It’s difficult to figure out how to build an incredibly sensitive infrared detector that you have to cram together on the back of a giant, foldable, gold covered mirror, sitting on a delicate, tennis-court-sized parasol, that can survive a rocket launch! It’s hard stuff!
And hundreds and hundreds of people around the world have been working on it together. JWST is the single most complicated science project human beings have ever attempted. But it’s been worth it. Because we want to discover the earliest galaxies in the universe, and clouds on other planets, and baby star-forming regions, and debris disks around stars, and weird dwarf galaxies, and supermassive black holes!
It’s been in development for almost thirty years and everyone is really ready for it! The James Webb Space Telescope is about to change astronomy. Get ready for discovery!
I am ready and excited! The JWST is currently set to launch no earlier than Dec 24, 2021. You can follow the progress of the launch here.
See also Looking back in time with the James Webb Space Telescope (60 Minutes) and 29 Days on the Edge. Oh and scientists have been working on this project for 20 years and are (understandably) really nervous about what happens with the launch.
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For the first time in human history, a spacecraft has flown through the Sun’s corona to collect data and capture samples (and, crucially, exited safely).
During the flyby, Parker Solar Probe passed into and out of the corona several times. This is proved what some had predicted — that the Alfvén critical surface isn’t shaped like a smooth ball. Rather, it has spikes and valleys that wrinkle the surface. Discovering where these protrusions line up with solar activity coming from the surface can help scientists learn how events on the Sun affect the atmosphere and solar wind.
Six panels of images taken from inside a coronal streamer. They appear grayish with white streaks showing particles in the solar wind.
At one point, as Parker Solar Probe dipped to just beneath 15 solar radii (around 6.5 million miles) from the Sun’s surface, it transited a feature in the corona called a pseudostreamer. Pseudostreamers are massive structures that rise above the Sun’s surface and can be seen from Earth during solar eclipses.
Passing through the pseudostreamer was like flying into the eye of a storm. Inside the pseudostreamer, the conditions quieted, particles slowed, and number of switchbacks dropped — a dramatic change from the busy barrage of particles the spacecraft usually encounters in the solar wind.
For the first time, the spacecraft found itself in a region where the magnetic fields were strong enough to dominate the movement of particles there. These conditions were the definitive proof the spacecraft had passed the Alfvén critical surface and entered the solar atmosphere where magnetic fields shape the movement of everything in the region.
The first passage through the corona, which lasted only a few hours, is one of many planned for the mission. Parker will continue to spiral closer to the Sun, eventually reaching as close as 8.86 solar radii (3.83 million miles) from the surface. Upcoming flybys, the next of which is happening in January 2022, will likely bring Parker Solar Probe through the corona again.
The video above provides a great overview of the origins, objectives, and motivations for the mission.
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Seán Doran took 78,846 frames of data compiled by the Solar Dynamics Observatory over the course of a month and made this absolutely fantastic time lapse of the Sun slowly rotating and burning and flaring. Put this on the biggest, high-resolution screen you can and pretend you’re in the solar observation room of the Icarus II in Sunshine.
See also A Decade of Sun and Gorgeous Time Lapse of the Sun. (via colossal)
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For the last nine months, NASA’s Perseverance rover has been rolling around on Mars taking photos and doing science. It’s also been recording audio of its environment with a pair of microphones and in this video, a pair of NASA scientists share some of those recordings and what we might learn about Mars from them.
This is one of my absolute favorite sounds. This is the sound of a helicopter flying on Mars. We used this sound to actually understand the propagation of sound in general through the Martian atmosphere, and it turns out that we were totally wrong with our models. The Martian atmosphere can propagate sound a lot further than we thought it could.
And surprisingly for me, that’s my friend Nina in the video! (We eclipse-chased together in 2017.) I knew she was working on the rovers but didn’t know she was going to pop up in this video I found on Twitter this morning. Fun!
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Marcella Giulia Pace photographed the Moon in 48 different hues and arranged them in a lovely spiral pattern.
I have collected some of my Full Moon shots taken over the past 10 years. I selected the shades of color with which the Moon was filmed in front of my lens and my eyes.
The atmosphere gives different colors to our satellite (scattering) based on its height with respect to the horizon, based on the presence of humidity or suspended dust. The shape of the Moon also changes: at the bottom of the horizon, refraction compresses the lunar disk at the poles and makes it look like an ellipse.
Prints of the image are available. (via @djacobs)
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The full moon was wonderful last night and Andrew McCarthy captured this colorful image of our nearest celestial companion. McCarthy explained where all those colors come from:
Back to this image, this was captured through a telescope and involved capturing thousands of frames to reveal the details. But what about the colors? The moon is gray, of course, but not *perfectly* gray. Some areas have a subtle blue tint, and others have a more orange tint. By teasing out those subtle colors, I can reveal the mineral composition of the moon! Blues denote titanium presence, while orange shows iron and feldspar present in the regolith. You can also see how impacts paint the surface with fresh color in the ejecta as they churn up material.
A print is available, but only for a very limited time (~6 more hours as of pub time).
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The Royal Museum Greenwich has announced the winners of the Astronomy Photographer of the Year for 2021. Zhong Wu won the galaxies category with a 360-degree view of the Milky Way (above, top), a mosaic which took two years to create — the northern hemisphere portion of the galaxy was photographed in China and the southern part in New Zealand. Jeffrey Lovelace’s photo of the crescent moon over Death Valley sand dunes (above, bottom) took the prize in the skyscapes category.
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I love this post from the NYPL comparing astronomical drawings by E.L. Trouvelot done in the 1870s to contemporary NASA images.
Trouvelot was a French immigrant to the US in the 1800s, and his job was to create sketches of astronomical observations at Harvard College’s observatory. Building off of this sketch work, Trouvelot decided to do large pastel drawings of “the celestial phenomena as they appear…through the great modern telescopes.”
He made drawings of Saturn, Jupiter, aurora borealis, the Milky Way, and more. Here’s his incredible drawing of sun spots compared to a recent image of the Sun’s surface:
And his drawing of a solar eclipse compared to a recent image:
Check out the post for more examples of Trouvelot’s work.
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Black holes are the largest single objects in the universe, many times larger than even the biggest stars, and have no upper limit to their size. But practically, how big is the biggest, heaviest black hole in the universe? (A: More massive than the entire Milky Way.)
The largest things in the universe are black holes. In contrast to things like planets or stars they have no physical size limit, and can literally grow endlessly. Although in reality specific things need to happen to create different kinds of black holes, from really tiny ones to the largest single things in the universe. So how do black holes grow and how large is the largest of them all?
Videos about space are where Kurzgesagt really shines. I’ve seen all their videos about black holes and related objects, and I always pick up something I never knew whenever a new one comes out. This time around, it was quasistars and the surprisingly small mass of supermassive black holes located at galactic centers compared to the galaxies themselves.
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As I’ve written before, in the history of astronomy and astrophysics, women have made major discoveries and played a significant role in advancing our understanding of the universe but have often not gotten the recognition their male peers enjoy. In 1967, while she was working on her doctoral research with her advisor Antony Hewish, Jocelyn Bell Burnell (then Jocelyn Bell) discovered a new and unusual kind of object, the pulsar. In this short documentary, Bell Burnell shares her story — how she got interested in radio astronomy, the prejudice with which she was treated as the only woman in her university program, how she discovered the first pulsar and persisted (more than once) through Hewish’s assertions that the object was “interference”, and how she was passed over for the Nobel Prize for her discovery.
In 2018, Bell Burnell was awarded the Special Breakthrough Prize in Fundamental Physics “for fundamental contributions to the discovery of pulsars, and a lifetime of inspiring leadership in the scientific community”, joining past honorees like the LIGO team, Stephen Hawking, and the team that discovered the Higgs boson. She donated the entire $3 million prize to the Institute of Physics to help support “PhD physics students from under-represented groups” with their educations.
It’s not justice, but I will note that Bell Burnell’s Wikipedia page is longer and more substantial than Hewish’s, despite his Nobel.
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