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kottke.org posts about space

Detailed Martian Geologic Maps from the USGS

geologic map of the Olympus Mons caldera on Mars

geologic map of the Aeolis Dorsa region of Mars

The USGS Astrogeology Science Center recently released a series of detailed geological maps of Mars that detail features from the red planet’s past like volcanos and flowing water. If you’re thinking, “hey that looks a lot like a river in that second image”, you’re not far off.

One particularly interesting feature that hints at Mars’ watery past is the sinuous ridge, which is a winding, narrow ridge that looks like an inverted river channel. These ridges are interpreted to be aqueous (formed by water), making them possible clues about the history of water on Mars.

The scale of the maps is useful for identifying geologic changes over time:

The new map of Aeolis Dorsa adds to the hypothesis that Mars was once wet and had abundant active river systems in the past before aqueous activity decreased over time. This change caused the primary depositional methods in the region to shift from rivers (fluvial) to sediment fans with intermittent deposition (alluvial) and eventually to a dry and wind-driven (aeolian) system. This local pattern mimics our current understanding of the global environmental history of Mars.

Lovely aesthetics as well. (via @geoffmanaugh)


A Soothing Hour of the Sun

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.


Our First Closeup Image of Mars Was a Paint-By-Numbers Pastel Drawing

Pastel drawing of the surface of Mars

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 β€” 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:

detail of a pastel drawing of the surface of Mars

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)


Some of the Best Moon & Earth Photos from NASA’s Artemis I Mission

photo of the Moon and Earth with the Artemis I spacecraft in the foreground

photo of the Moon and Earth with the Artemis I spacecraft in the foreground

close-up of the lunar surface

photo of the Earth with the Artemis I spacecraft in the foreground

close-up of the lunar surface

photo of the Moon with the Artemis I spacecraft in the foreground

photo of the Moon and Earth with the Artemis I spacecraft in the foreground

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 β€” 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) β€” you can see a bigger version of it here.


Mars Helicopter Spots Perseverance Rover’s Landing Debris

wreckage from the landing of NASA's Perseverance rover on Mars

wreckage from the landing of NASA's Perseverance rover on Mars

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 β€” at 70.5 feet (21.5 meters) wide, it was the biggest ever deployed on Mars β€” 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.


NASA’s Perseverance Rover Sees Solar Eclipse on Mars

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 β€” 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.


High-Res View of a Martian Crater

SeΓ‘n 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 β€” worth taking a second or third pass to catch all the details.


The Highest Resolution Photo of the Sun Ever Taken

very high resolution image of the Sun

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.


How Saturn Got Its Rings

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.


Apollo 10 1/2

From Richard Linklater (Boyhood, A Scanner Darkly) comes a new Netflix movie called Apollo 10 1/2, in which a young boy growing up in Houston, TX in the 60s gets recruited by NASA to land a accidentally-too-small lunar lander on the Moon. It’s animated1 and premieres on Netflix on April 1.

  1. The movie is rotoscoped, like Linklater’s A Scanner Darkly. I have to say, the rotoscoping effect is not my favorite. Why couldn’t this have been live action? I bet it would find more of an audience that way…↩


How the James Webb Space Telescope Orbits Nothing

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.


Voyage of the Moons

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 β€” 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 β€” it looks totally rendered. Also in the video is footage of Titan orbiting Saturn β€” that horizontal line bisecting the frame is Saturn’s rings, edge-on.


How Does The James Webb Space Telescope Work?

The James Webb Space Telescope is still winging its way to its permanent home at the L2 point1 about 930,000 miles from Earth β€” 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 β€” I can’t wait to see what the telescope sees once it’s fully operational.

  1. You can read about Lagrange points here or here…they are interesting!↩


Gorilla in Space

Astronaut Scott Kelly arranged to have a gorilla suit sent up to him during his year spent on the International Space Station. One day, near the end of the mission in 2016, he put it on, stowed away in a large storage container, and then escaped and went on a “rampage”.


Powers of Ten, Updated With Current Science

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 β€” into the hand of the sleeping picnicker β€” 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 β€” you can zoom in and out as far as you want and interact with and learn about objects along the way.


A Close-Up Photo of Comet Leonard by an Amateur Astronomer

Comet Leonard

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.


The Dark Forest (Or, Why We Should Keep Still and Not Look for Aliens)

Inspired by the second book in Liu Cixin’s excellent Three-Body Problem trilogy, Kurzgesagt made a video about the Dark Forest solution to the Fermi paradox.

Confronted with the seemingly empty universe, humanity faces a dilemma. We desperately want to know if we are alone in the Milky Way. We want to call out and reveal ourselves to anyone watching but that could be the last thing we ever do. Because maybe the universe is not empty. Maybe it’s full of civilizations but they are hiding from each other. Maybe the civilizations that attracted attention in the past were wiped away by invisible arrows. This is the Dark Forest solution to the Fermi paradox.

I have The Dark Forest on the Kindle, so I looked up how this is explained in the book (spoilers, obvs):

“The universe is a dark forest. Every civilization is an armed hunter stalking through the trees like a ghost, gently pushing aside branches that block the path and trying to tread without sound. Even breathing is done with care. The hunter has to be careful, because everywhere in the forest are stealthy hunters like him. If he finds other life-another hunter, an angel or a demon, a delicate infant or a tottering old man, a fairy or a demigod-there’s only one thing he can do: open fire and eliminate them. In this forest, hell is other people. An eternal threat that any life that exposes its own existence will be swiftly wiped out. This is the picture of cosmic civilization. It’s the explanation for the Fermi Paradox.”

Shi Qiang lit another cigarette, if only to have a bit of light.

“But in this dark forest, there’s a stupid child called humanity, who has built a bonfire and is standing beside it shouting, ‘Here I am! Here I am!’” Luo Ji said.

“Has anyone heard it?”

“That’s guaranteed. But those shouts alone can’t be used to determine the child’s location. Humanity has not yet transmitted information about the exact position of Earth and the Solar System into the universe. From the information that has been sent out, all that can be learned is the distance between Earth and Trisolaris, and their general heading in the Milky Way. The precise location of the two worlds is still a mystery. Since we’re located in the wilderness of the periphery of the galaxy, we’re a little safer.”

That’s the basic idea, but there’s more to it…you should watch the video or, even better, read the series β€” I’ve read the entire trilogy twice and this makes me want to read it again! (I loved the Drive Easter egg towards the end of the video. Well played.)


This Is A Film About The James Webb Space Telescope

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.


A NASA Spacecraft Has Touched the Sun

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 β€” that the AlfvΓ©n 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 β€” 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 AlfvΓ©n 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.


One Month of the Sun

SeΓ‘n 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)


Cosmic Relaxation

Eight hours of ambient chillout music over images pulled from NASA’s photographic archive of nebulas, galaxies, planets, and other celestial objects? Sure, I’m in.

See also Hours and Hours of Relaxing & Meditative Videos.


Orbital Planes, a Photographic Ode to the Space Shuttle

closeup photo of the Space Shuttle Discovery

Space Shuttle instrument panel

Roland Miller has been documenting space exploration for more than 30 years and his latest book, which he’s funding via Kickstarter, is a photo documentation of the final years of NASA’s Space Shuttle program.

I started documenting the Space Shuttle program when I was teaching photography at a college near the Kennedy Space Center. In 2008, I began a concentrated effort to document the final years of the program. Orbital Planes is the result of that photography work. My hope is that Orbital Planes will give the reader their own personal view of the Space Shuttle and the technology and facilities that helped it fly.

You might remember Miller from his collaboration with Italian astronaut Paolo Nespoli photographing the ISS. (via colossal)


The Sounds from Mars

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!


Captain Kirk Goes to Space: “It’s Indescribable”

Last week, William Shatner finally got a chance to boldly go where he hadn’t actually been before: into space. And upon returning from the 11-minute flight, the 90-year-old TV spaceship captain had come down with more than a touch of the Overview Effect. From the transcript of his post-flight remarks:

If…. Everybody in the world needs to do this…

Everybody in the world needs to see the…” (begins to cry) “…It was unbelievable, unbelievable. I mean, you know the little things… weightlessness… to see the blue color just.. go WHIP by!!! And now you’re staring into blackness. That’s the thing… the covering of blue… this sheet, this blanket, this comforter of blue that we have around us. We think, ‘Oh, that’s blue the sky!’

And then suddenly you shoot up through it all of the sudden… as if you whip off the sheet off you when you are asleep and you’re looking into blackness. Into BLACK UGLINESS… And you look down and there’s the blue down there… and the black up there and it’s… it’s just… there is Mother Earth… and comfort… and there is ….is there death? I don’t know! Is that death? Is that the way death is?? WOOP, and it’s gone! Jesus…

It was so moving to me… this experience …it’s something unbelievable. You see it… yeah, you know… weightlessness… my stomach went up and I thought, ‘God, this is so weird…’ but not as weird as the covering of blue… this is what I never expected. Oh, it’s one thing to say, ‘Oh… the sky and the thing and the… gradual…’ It’s all true… but what isn’t true… what is unknown until you do it is… is this pillow.. There’s this soft blue… look at the the beauty of that color! And it’s so THIN! And you’re through it in an instant…

He continued:

I don’t know, I can’t even begin to express what I …what I would love to do is to communicate as much as possible … the jeopardy… the the the moment you see how… The vulnerability of everything, it’s so… small. This AIR which is keeping us alive is thinner than your skin! It’s… it’s a… it’s a sliver! It’s immeasurably small when you think in terms of the Universe! It’s negligible! This air… Mars doesn’t have it! No… nothing… I mean, this…

They should have sent a poet. Jokes aside, I’m sure that if I’d just returned from a flight into space, I’d would be equally flummoxed and unable to articulate what I’d just experienced. Hell, I couldn’t even talk after seeing a solar eclipse.


The Many Colors of the Moon

the Moon in 48 different colors, arranged in a spiral shape

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)


Full Moon

a full moon with a very colorful surface

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).


The Astronomy Photographer of the Year for 2021

360-degree view of the Milky Way galaxy

the crescent moon rising over the desert

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 β€” 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.


1800s Astronomical Drawings vs. Modern NASA Images

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:

a drawing of sun spots

the sun

And his drawing of a solar eclipse compared to a recent image:

a drawing of a total solar eclipse

modern photo of a solar eclipse

Check out the post for more examples of Trouvelot’s work.


Size Comparison: The Largest Black Hole in the Universe

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.


The 2021 Astronomy Photographer of the Year Shortlist

solar flares shooting off the surface of the Sun

panorama of the aurora borealis in the winter

panorama of the Milky Way over a lavender field

The Royal Museums Greenwich has announced the shortlist for the 2021 Astronomy Photographer of the Year competition. I’ve included a few favorites above (by Andrew McCarthy, Larryn Rae, and Stefan Liebermann) but you can check out the rest on their site. (via curious about everything)