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kottke.org posts about astronomy

Recently Discovered Comet Might Put On a Show

posted by Jason Kottke   Mar 23, 2020

Back in late December, a new comet called Comet ATLAS (or C/2019 Y4) was discovered by a robotic astronomical survey on the lookout for objects that may strike the Earth. Don’t worry, Comet ATLAS isn’t going to hit us, but it has a chance to put on quite a show.1 It didn’t seem like much at first, but since its discovery Comet ATLAS has gotten brighter much faster than scientists have expected.

When astronomers first spotted Comet ATLAS in December, it was in Ursa Major and was an exceedingly faint object, close to 20th magnitude. That’s about 398,000 times dimmer than stars that are on the threshold of naked-eye visibility. At the time, it was 273 million miles (439 million kilometers) from the sun.

But comets typically brighten as they approach the sun, and at its closest, on May 31, Comet ATLAS will be just 23.5 million miles (37.8 million km) from the sun. Such a prodigious change in solar distance would typically cause a comet to increase in luminosity by almost 11 magnitudes, enough to make ATLAS easily visible in a small telescope or a pair of good binoculars, although quite frankly nothing really to write home about.

Except, since its discovery, the comet has been brightening at an almost unprecedented speed. As of March 17, ATLAS was already magnitude +8.5, over 600 times brighter than forecast. As a result, great expectations are buzzing for this icy lump of cosmic detritus, with hopes it could become a stupendously bright object by the end of May.

But the brightening could also be a sign that the comet is ejecting a lot of material because it’s burning itself out, so grain of salt. But if keeps brightening at a good pace, it could be visible during the day in the northern hemisphere.

If Atlas manages to remain intact, some in the field have suggested it could grow from magnitude +1 to possibly -5. At the brightest extreme, it could be visible even during the day.

The location of the comet is also notable-unlike more recent comets, it will be best viewed in the Northern Hemisphere.

Chuck Ayoub recently captured the comet arcing across the night sky with his backyard astrophotography rig:

Oh I hope Comet ATLAS can keep it together. I vividly remember going outside in rural Wisconsin darkness to see the tail of Comet Hyakutake stretch halfway across the sky. One of the most amazing things I’ve ever seen.

  1. Although I guess Comet ATLAS is good news if you’re looking for signs of the apocalypse too. Pandemic: check. Bright new light in the sky: check.

Mysterious Sources of Light Pollution

posted by Jason Kottke   Mar 06, 2020

If you look at online light pollution maps, most light pollution comes from cities, but Alex Altair noticed that there are some unexpected sources of light out there as well. For instance, this sprawling site in North Dakota is one of the brightest places in the country despite what Altair calls “an intense lack of urbanization”.

Light pollution in North Dakota

The light in that area is from oil drilling & extraction in the area.

The light pollution comes from the associated gas flares. These flares are deliberate, continuously burning fires, and they convert methane, a potent greenhouse gas, into CO2, a much less potent greenhouse gas.

Intense heat also accounts for an odd light source in Hawaii — you can probably guess, but you’ll have to click through to confirm.

See also Lost in Light: How Light Pollution Obscures Our View of the Night Sky.

The Curiosity Rover Captures a 1.8 Gigapixel Panorama of Mars

posted by Jason Kottke   Mar 05, 2020

Mars Curiosity Pano

Late last year, NASA’s Curiosity rover took over a thousand photos of the Martian landscape while exploring a mountainside. NASA stitched the photos together and recently released this 1.8 gigapixel panorama of Mars (along with a mere 650 megapixel panorama, pictured above). Here’s a version you can pan and zoom:

And a narrated video of the panorama:

Both panoramas showcase “Glen Torridon,” a region on the side of Mount Sharp that Curiosity is exploring. They were taken between Nov. 24 and Dec. 1, when the mission team was out for the Thanksgiving holiday. Sitting still with few tasks to do while awaiting the team to return and provide its next commands, the rover had a rare chance to image its surroundings from the same vantage point several days in a row.

I like how NASA is casually suggesting that the rover is just kinda taking some vacation snaps while waiting on friends.

Linguistic Constellations

posted by Jason Kottke   Mar 04, 2020

Linguistic Constellations

Linguistic Constellations

Illustrator Jerry M. Wilson has drawn a series of constellations that explore the etymology of the constellations’ names and related words in several languages. So for example, “Taurus” is Latin for “bull”, which is “toro” in Spanish & Italian and “tyr” in Danish. And then you also have associated words like “toreador” (“bullfighter” in Spanish) and “teurastamo” (Finnish for “slaughterhouse”)…a constellation of words related to “Taurus”.

Universe Sandbox

posted by Jason Kottke   Feb 14, 2020

Universe Sandbox is a interactive space & gravity simulator that you can use to play God of your own universe.

You can create star systems: “Start with a star then add planets. Spruce it up with moons, rings, comets, or even a black hole.” You can collide planets and stars or simulate gravity: “N-body simulation at almost any speed using Newtonian mechanics.” You can model the Earth’s climate, make a star go supernova, or ride along on space missions or see historical events.

I found Universe Sandbox after watching this video about what would happen if the Earth got hit by a grain of sand going 99.9% the speed of light (spoiler: not much). This game/simulator/educational tool is only $30 but I fear that if I bought it, I would never ever leave the house again.

New Solar Telescope Shows the Sun’s Surface in Unprecendented High Resolution Images & Video

posted by Jason Kottke   Jan 29, 2020

Sun's Surface

Sun's Surface

The National Science Foundation has just released the very first images of the Sun taken with the new Inouye Solar Telescope in Hawaii. They are the highest resolution images ever taken of the Sun’s surface, showing three times more detail than was possible using previous imaging techniques. Those cells you see in the image…they’re each about the size of Texas.

Building a telescope like this is not an easy task — there’s a lot of heat to deal with:

To achieve the proposed science, this telescope required important new approaches to its construction and engineering. Built by NSF’s National Solar Observatory and managed by AURA, the Inouye Solar Telescope combines a 13-foot (4-meter) mirror — the world’s largest for a solar telescope — with unparalleled viewing conditions at the 10,000-foot Haleakala summit.

Focusing 13 kilowatts of solar power generates enormous amounts of heat — heat that must be contained or removed. A specialized cooling system provides crucial heat protection for the telescope and its optics. More than seven miles of piping distribute coolant throughout the observatory, partially chilled by ice created on site during the night.

Scientists have released a pair of mesmerizing time lapse videos as well, showing ten minutes of the roiling surface of the Sun (wide angle followed by a close-up view) in just a few seconds:

The Daniel K. Inouye Solar Telescope has produced the highest resolution observations of the Sun’s surface ever taken. In this movie, taken at a wavelength of 705nm over a period of 10 minutes, we can see features as small as 30km (18 miles) in size for the first time ever. The movie shows the turbulent, “boiling” gas that covers the entire sun. The cell-like structures — each about the size of Texas — are the signature of violent motions that transport heat from the inside of the sun to its surface. Hot solar material (plasma) rises in the bright centers of “cells,” cools off and then sinks below the surface in dark lanes in a process known as convection. In these dark lanes we can also see the tiny, bright markers of magnetic fields. Never before seen to this clarity, these bright specks are thought to channel energy up into the outer layers of the solar atmosphere called the corona. These bright spots may be at the core of why the solar corona is more than a million degrees!

Man, I hope we get some longer versions of these time lapses — I would watch the hell out of one that ran for 10 minutes. (via moss & fog)

An Astronomer Explains Black Holes in 5 Levels of Increasing Complexity

posted by Jason Kottke   Jan 21, 2020

In this video from Wired’s 5 Levels series, NASA astronomer Varoujan Gorjian explains the concept of black holes to five different people, ranging from a five-year-old to a college student to a Caltech astrophysicist.

A research astronomer at NASA’s Jet Propulsion Laboratory, Grojian specializes in — and I’d just like to pause here to emphasize that this is the official title of his research group at JPL — the structure of the universe. Which means the guy not only knows about event horizons and gravitational lensing but stuff like tidal forces (what!), x-ray binaries (hey now!), and active galactic nuclei (oh my god!). Seriously, the guy’s knowledge of black holes is encyclopedic.

Gorjian lost me somewhere in the middle of his conversation with the grad student.

This Striking Image of the Moon Is a Combination of 100,000 Photos

posted by Jason Kottke   Jan 15, 2020

Backyard astronomer Andrew McCarthy has created some arresting images of various objects in the sky, including galaxies, planets, the Sun, and nebulas. Perhaps his favorite subject is the Moon and for one of his first images of 2020, he combined 100,000 photos to make this image of the first quarter Moon.

Andrew McCarthy Moon

Some detail:

Andrew McCarthy Moon

*low whistle* McCarthy uses some digital darkroom techniques to bump up the dynamic range, which he explained in the comments of a similar image.

The natural colors of the moon were brought out here with minor saturation adjustments, but those colors are completely real and what you could see if your eyes were more sensitive. I find the color really helps tell the story of how some of these features formed billions of years ago.

In one of his Instagram Stories, he shows how he photographs the Moon, including dealing with temperature changes over the course of the session — “when it’s cold, the telescope shrinks, and the focus changes”.

McCarthy sells digital copies of his images (as wallpaper or to print out) as well as prints. (via moss & fog)

Cecilia Payne-Gaposchkin, a Giant of Physics

posted by Jason Kottke   Dec 17, 2019

Prompted by this Facebook post, I have been reading about astrophysicist Cecilia Payne-Gaposchkin, who should be more widely known than she is. From a piece last year in Cosmos:

Cecilia Payne, born on May 10, 1900, in Wendover, England, began her scientific career in 1919 with a scholarship to Cambridge University, where she studied physics. But in 1923 she received a fellowship to move to the United States and study astronomy at Harvard. Her 1925 thesis, Stellar Atmospheres, was described at the time by renowned Russian-American astronomer Otto Struve as “the most brilliant PhD thesis ever written in astronomy”.

In the January, 2015, Richard Williams of the American Physical Society, wrote: “By calculating the abundance of chemical elements from stellar spectra, her work began a revolution in astrophysics.”

Even though she completed her studies at Cambridge, she was not awarded a degree because the university did not give degrees to women. That’s when she decided to move to the US, where Harvard offered greater educational opportunities and a “collection of several hundred thousand glass photographs of the night sky” that Payne-Gaposchkin was uniquely qualified to analyze.

Miss Payne applied the new theories of atomic structure and quantum physics to her analysis of stellar spectra. No one at the Harvard Observatory had yet attempted such an investigation, as no one there possessed the necessary background. She, in contrast, had learned the complex architecture of the “Bohr atom” directly from Niels Bohr, winner of the 1922 Nobel Prize in physics. She had also followed the work of Indian physicist Meg Nad Saha of Calcutta, the first person to link the atom to the stars. Saha maintained that the line patterns in stellar spectra differed according to the temperatures of the stars. The hotter the star, the more readily the electrons of its atoms leaped to higher orbits. With sufficient heat, the outermost electrons broke free, leaving behind positively charged ions with altered spectral signatures.

Building on Saha’s base, with insights gained from a couple of her professors in England, Miss Payne selected specific spectral lines to examine. Then she estimated their intensities in hundreds of stellar spectra. Element by element she gauged, plotted, and calculated her way through the plates to take the temperatures of the stars.

Her groundbreaking work on spectra, laid out in her Ph.D thesis published when she was just 25, puts Payne-Gaposchkin in the same league as some other physics heavy hitters.

Her discovery of the true cosmic abundance of the elements profoundly changed what we know about the universe. The giants — Copernicus, Newton, and Einstein — each in his turn, brought a new view of the universe. Payne’s discovery of the cosmic abundance of the elements did no less.

The Relative Rotations of the Planets

posted by Jason Kottke   Dec 11, 2019

Planetary scientist James O’Donoghue made this cool little visualization of the rotation speeds of the planets of the solar system. You can see Jupiter making one full rotation every ~10 hours, Earth & Mars about every 24 hours, and Venus rotating once every 243 days. He also did a version where all the planets rotate the same way (Venus & Uranus actually rotate the other way).

See also O’Donoghue’s visualizations of the speed of light that I posted back in January.

Every Kind of Thing in Space

posted by Jason Kottke   Dec 02, 2019

This 12-minute animated video is a tour of all of the different kinds of things “out there” in the universe (as opposed to matter and structures smaller than, say, a human being).

This video explores all of the things in the Universe from our Earth and local Solar System, out to the Milky Way Galaxy and looks at all of the different kinds of stars from Brown Dwarfs to Red Supergiant Stars. Then to the things they explode into like white dwarfs, neutron stars and black holes. Then we look at all the other kinds of galaxy in the universe, blazars, quasars and out to the cosmic microwave background and the big bang. It covers most of the different things that we know about in the Universe.

A poster of the final drawing is available here.

How to Watch Tonight’s Rare Unicorn Meteor Storm

posted by Jason Kottke   Nov 21, 2019

Astronomers are expecting a particularly strong meteor storm tonight visible from parts of Europe, Africa, North America, and South America that could produce meteors at a rate of 400/hour or more. The storm’s radiant will be centered right around the constellation of Monoceros (that’s the unicorn, which makes this a very 2019 event). Just find Orion in the eastern sky and look a bit down and to the left, right where the red patch is:

Meteor Storm 2019

If you’re on the east coast of the US and the sky is clear tonight, you should head outside around 11:15pm EST. And be prompt…the storm’s peak activity will last 15-40 minutes. I’m going to see if Night Mode on my iPhone 11 Pro can capture any of the action…

See also the time I saw a boomerang meteor explode like a firework in the night sky. (thx, megan)

Neutron Stars and Nuclear Pasta. Yummy!

posted by Jason Kottke   Nov 13, 2019

The latest video from Kurzgesagt is a short primer on neutron stars, the densest large objects in the universe.

The mind-boggling density of neutron stars is their most well-known attribute: the mass of all living humans would fit into a volume the size of a sugar cube at the same density. But I learned about a couple of new things that I’d like to highlight. The first is nuclear pasta, which might be the strongest material in the universe.

Astrophysicists have theorized that as a neutron star settles into its new configuration, densely packed neutrons are pushed and pulled in different ways, resulting in formation of various shapes below the surface. Many of the theorized shapes take on the names of pasta, because of the similarities. Some have been named gnocchi, for example, others spaghetti or lasagna.

Simulations have demonstrated that nuclear pasta might be some 10 billion times stronger than steel.

The second thing deals with neutron star mergers. When two neutron stars merge, they explode in a shower of matter that’s flung across space. Recent research suggests that many of the heavy elements present in the universe could be formed in these mergers.

But how elements heavier than iron, such as gold and uranium, were created has long been uncertain. Previous research suggested a key clue: For atoms to grow to massive sizes, they needed to quickly absorb neutrons. Such rapid neutron capture, known as the “r-process” for short, only happens in nature in extreme environments where atoms are bombarded by large numbers of neutrons.

If this pans out, it means that the Earth’s platinum, uranium, lead, and tin may have originated in exploding neutron stars. Neat!

A Solar Eclipse from the Edge of Space

posted by Jason Kottke   Nov 08, 2019

For a BBC series called Earth from Space, the team at Sent Into Space attached a VR camera to a balloon and sent it up to an altitude of about 20 miles — high enough to see the blackness of space and Earth’s curvature — to take a 360° video of the total solar eclipse that occurred in August 2017. The video above is a hyperlapse of the event while this one from the BBC is slower, annotated, and in full 360° VR.

See also Patrick Cullis’ epic adventure in trying to snap a photo of the total solar eclipse from the edge of space. (via @alexkorn)

The Milky Way Reflected in the World’s Largest Mirror

posted by Jason Kottke   Oct 29, 2019

Jheison Huerta

I love this photograph by Peruvian photographer Jheison Huerta. It’s a shot of the Milky Way above the Salar de Uyuni salt flat in Bolivia. After it rains, the thin layer of water transforms the flat into the world’s largest mirror, some 80 miles across. Beautiful.

See also The Entire Plane of the Milky Way Captured in a Single Photo. (via astronomy picture of the day)

Behold Our Dazzling Night Sky When the Milky Way Collides with Andromeda in 4 Billion Years

posted by Jason Kottke   Oct 21, 2019

This is what our night sky is going to look like in 3.9 billion years:

Milkdromeda

Wow! So what’s going on here? Using data from the Hubble Space Telescope, astronomers at NASA have predicted that our own Milky Way galaxy and the nearby Andromeda galaxy (M31) will collide about 4 billion years from now. As part of the announcement from 2012, they produced a video of what the collision would look like and a series of illustrations of what our sky will look like during the collision process.1

In 2 billion years, Andromeda will be noticeably closer in the sky:

Milkdromeda

By 3.75 billion years, it will fill a significant chunk of the sky. And the Milky Way will begin to bend due to the pull of gravity from Andromeda:

Milkdromeda

In about 3.85 billion years, the first close approach will trigger the formation of new stars, “which is evident in a plethora of emission nebulae and open young star clusters”:

Milkdromeda

Star formation continues 3.9 billion years from now. Could you imagine actually going outside at night and seeing this? It’s like a nightly fireworks display:

Milkdromeda

After the galaxies pass by each other in 4 billion years, they are stretched and warped by gravity:

Milkdromeda

In 5.1 billion years, Andromeda and the Milky Way will come around for a second close pass, their galactic cores blazing bright in the night sky:

Milkdromeda

And finally, in 7 billion years, the two galaxies will have merged into a single elliptical galaxy nicknamed Milkdromeda:

Milkdromeda

Interestingly, despite the galactic collision and the dazzling view from Earth, it’s extremely unlikely that any individual stars will collide because of the sheer amount of empty space in galaxies.

  1. I mean, assuming there will still be someone or something standing on the Earth 4 billion years from now to witness it. Presumably whoever’s around will have solved light pollution by then? The bigger worry is that according to the timeline of the far future, Earth will be uninhabitable long before an collision occurs (average surface temp of 296 °F in 2.8 billion years). Toasty!

The First Photograph of the Far Side of the Moon from 1959

posted by Jason Kottke   Oct 02, 2019

With the launch of Sputnik in 1957, the Soviet Union kicked off the Space Race and for the first several years (arguable up until the Moon landing in ‘69), they dominated the United States. One of their “firsts” in the early years was taking the first photo of the far side of the Moon 60 years ago this month.

Dark side of the Moon 1959

Astronomer Kevin Hainline wrote a fascinating account of how the Soviet’s Luna 3 spacecraft took the photo and then transmitted it back to Earth.

First off, Luna 3, the first three-axis stabilized spacecraft, had to reach the Moon to take the pictures, and it had to use a little photocell to orient towards the Moon so that now, while stabilized, it could take the pictures. Which it did. On PHOTOGRAPHIC FILM.

And it gets WILDER because these photos were then moved to a little CHEMICAL PLANT to DEVELOP AND DRY THEM. That’s right, Luna 3 had a little 1 Hour Photo inside. Now you’re thinking, well, how do you get those actual photos back to the Earth?

How indeed? The spacecraft faxed the photos to Earth. A few years later, when the Soviets’ Luna 9 took the first photo on the Moon’s surface and went to transmit it back to Earth, a group in the UK was able to read the signal with a fax machine and the resulting image was published the next day on the front page of the Daily Express.

The Comet

posted by Jason Kottke   Sep 06, 2019

Director Christian Stangl and composer Wolfgang Stangl used millions of photos (that’s right, millions!) taken by the ESA’s Rosetta spacecraft of Comet 67P/Churyumov-Gerasimenko to make this short video that makes the mission feel like sci-fi a la Alien or District 9.

The Hubble’s New Portrait of Jupiter

posted by Jason Kottke   Aug 27, 2019

Jupiter Hubble 2019

A photo of Jupiter taken by the Hubble Space Telescope in late June was recently released by NASA. Among other things, it shows just how much smaller, redder, and rounder the Great Red Spot has gotten.

The Great Red Spot is a towering structure shaped like a wedding cake, whose upper haze layer extends more than 3 miles (5 kilometers) higher than clouds in other areas. The gigantic structure, with a diameter slightly larger than Earth’s, is a high-pressure wind system called an anticyclone that has been slowly downsizing since the 1800s. The reason for this change in size is still unknown.

The spot was “once big enough to swallow three Earths with room to spare” but has been shrinking steadily since a brief expansion in the 1920s. As the storm contracts, it has stretched up into the Jovian atmosphere.

Because the storm has been contracting, the researchers expected to find the already-powerful internal winds becoming even stronger, like an ice skater who spins faster as she pulls in her arms.

Instead of spinning faster, the storm appears to be forced to stretch up. It’s almost like clay being shaped on a potter’s wheel. As the wheel spins, an artist can transform a short, round lump into a tall, thin vase by pushing inward with his hands. The smaller he makes the base, the taller the vessel will grow.

Recently amateur astronomers have observed “flakes” or “blades” coming off of the storm and dissipating into the larger atmosphere, a formerly rare phenomenon that now seems more common.

The Hubble photographs also yielded a rotating view of the planet as well as a very cool stretched-out photo of the surface:

Jupiter Hubble 2019 Stretch

The Entire Plane of the Milky Way Captured in a Single Photo

posted by Jason Kottke   Aug 26, 2019

Entire Galaxy

By photographing two separate nighttime scenes, one in the northern hemisphere and the other in the southern hemisphere, amateur astrophotographer Maroun Habib cleverly produced this dazzling image of the complete galactic plane visible from Earth.

Is it possible to capture the entire plane of our galaxy in a single image? Yes, but not in one exposure — and it took some planning to do it in two. The top part of the featured image is the night sky above Lebanon, north of the equator, taken in 2017 June. The image was taken at a time when the central band of the Milky Way Galaxy passed directly overhead. The bottom half was similarly captured six months later in latitude-opposite Chile, south of Earth’s equator. Each image therefore captured the night sky in exactly the opposite direction of the other, when fully half the Galactic plane was visible.

See also The Earth Rotating Beneath a Stationary Milky Way, which went viral after I posted it two weeks ago. (via @surfinsev)

Recreating the sun’s plasma in a laboratory

posted by Patrick Tanguay   Aug 02, 2019

Sun's plasma

Since it’s quite hard to study the sun, “a team of researchers decided to try to re-create the sun’s magnetic field structure in a ball of plasma in their laboratory.” Although the conditions were obviously quite different and their model incomplete, they did manage to delve deeper into how the magnetic field of the sun works and how our star’s plasma flows through it.

The sun’s magnetic fields form enormous loops that extend from the sun’s surface into space. Some of these loops are small enough to fit entirely within the sun’s corona, while others stretch to the edges of the solar system.

The experiment was also able to mimic a region around the sun where the plasma hangs in a precarious balance. Within this boundary, plasmas are contained by magnetic fields, but outside it, centrifugal forces from the sun’s rotation overpower the magnetic fields, and plasmas stream outward. The researchers found that “if you spin [the plasma] hard enough, you can get it to spin out from centrifugal force.”

Note: The image up top is an image captured from the video in the article, make sure to click through and admire.

What Neil Armstrong Saw from His Window As He Landed on the Moon

posted by Jason Kottke   Jul 22, 2019

I was away this weekend at a family function and mostly without internet access, so I didn’t get to watch the coverage of the Moon landing for the first time in more than a decade. I also didn’t get to share a bunch of links I had up in browser tabs and now I think everyone is (justifiably) tired of all the Apollo 11 hoopla, myself included. But I hope you’ll indulge me in just one more and then I’ll (maybe! hopefully!) shut up about it for another year.

It’s tough to narrow it down, but the most dramatic & harrowing part of the whole mission is when Neil Armstrong notices that the landing site the LM (call sign “Eagle”) is heading towards is no good — it’s too rocky and full of craters — so he guides the spacecraft over that area to a better landing spot. He does this despite never having flown the LM that way in training, with program alarms going off, with Mission Control not knowing what he’s doing (he doesn’t have time to tell them), and with very low fuel. Eagle had an estimated 15-20 seconds of fuel left when they touched down and the guy doing the fuel callouts at Mission Control was basically just estimating the remaining fuel in his head based on how much flying he thinks the LM had done…and again, the LM had never been flown like that before and Mission Control didn’t know what Armstrong was up to! (The 13 Minutes to the Moon podcast does an excellent job explaining this bit of the mission, episode 9 in particular.)

Throughout this sequence, there was a camera pointed out Buzz Aldrin’s window — you can see that video here — but that was a slightly different view from Armstrong’s. We’ve never seen what Armstrong saw to cause him to seek out a new landing site. Now, a team at NASA has simulated the view out of his window using data from the Lunar Reconnaissance Orbiter Camera:

The LROC team reconstructed the last three minutes of the landing trajectory (latitude, longitude, orientation, velocity, altitude) using landmark navigation and altitude call outs from the voice recording. From this trajectory information, and high resolution LROC NAC images and topography, we simulated what Armstrong saw in those final minutes as he guided the LM down to the surface of the Moon. As the video begins, Armstrong could see the aim point was on the rocky northeastern flank of West crater (190 meters diameter), causing him to take manual control and fly horizontally, searching for a safe landing spot. At the time, only Armstrong saw the hazard; he was too busy flying the LM to discuss the situation with mission control.

This reconstructed view was actually pretty close to the camera’s view out of Aldrin’s window:

See also a photograph of the Apollo 11 landing site taken by the LRO camera from a height of 15 miles.

The Atlas of Moons

posted by Jason Kottke   Jul 11, 2019

Atlas Of Moons

From National Geographic comes The Atlas of Moons, an interactive reference to all of the major moons in our solar system, from the Earth’s own moon to the Galilean moons of Jupiter to Charon, which forms a binary system with Pluto.

For whatever reason, I wasn’t fully aware that some of Jupiter’s and Saturn’s major moons orbited their planets so quickly — Europa takes 3.6 days to complete an orbit, Io once every 1.8 days, and Mimas speeds around Saturn every 22.6 hours.

How to Watch the South American Solar Eclipse

posted by Jason Kottke   Jul 02, 2019

Today, July 2, 2019, just after 4:30pm ET, a total solar eclipse will be visible in parts of Chile and Argentina. Because most of you, I am guessing, are not currently in those parts of Chile and Argentina, the best way to watch the eclipse is through any number of live streams, three of which I’m embedding here:

I was lucky enough to see the eclipse in 2017 and it was a life-altering experience, so I’ll be tearing myself away from the USA vs England match for a few minutes at least.

The First Film Footage of a Total Solar Eclipse (1900)

posted by Jason Kottke   May 30, 2019

The BFI and the Royal Astronomical Society have recently rediscovered and restored a film taken in 1900 of a total solar eclipse. Here’s the minute-long film on YouTube:

The film was taken by British magician turned pioneering filmmaker Nevil Maskelyne on an expedition by the British Astronomical Association to North Carolina on 28 May, 1900. This was Maskelyne’s second attempt to capture a solar eclipse. In 1898 he travelled to India to photograph an eclipse where succeeded but the film can was stolen on his return journey home. It was not an easy feat to film. Maskelyne had to make a special telescopic adapter for his camera to capture the event. This is the only film by Maskelyne that we know to have survived.

The Royal Astronomy Society will be showing the film tomorrow May 31 at their HQ in London as part of their celebration of the centenary of the 1919 eclipse; free tickets available here.

See also my account of going to see the 2017 solar eclipse, one of the coolest things I’ve ever done. (via @UnlikelyWorlds)

A Short History of Black Holes on Radio Telescopes

posted by Tim Carmody   Apr 12, 2019

So, you’ve probably heard by now that we have our first ever photographs of a black hole and its event horizon. But it’s not like black holes have just been theoretical entities this entire time, awaiting photography’s blessing to finally be anointed as real. We’ve been detecting black holes for a long time now using radio telescopes and infrared cameras. It may be outside the visible spectrum, but that doesn’t mean it ain’t real, son!

The story begins in the mid-1900s when astronomers expanded their horizons beyond the very narrow range of wavelengths to which our eyes are sensitive. Very strong sources of radio waves were discovered and, when accurate positions were determined, many were found to be centered on distant galaxies. Shortly thereafter, radio antennas were linked together to greatly improve angular resolution. These new “interferometers” revealed a totally unexpected picture of the radio emission from galaxies—the radio waves did not appear to come from the galaxy itself, but from two huge “lobes” symmetrically placed about the galaxy….

Ultimately this led to the technique of Very Long Baseline Interferometry (VLBI), in which radio signals from antennas across the Earth are combined to obtain the angular resolution of a telescope the size of our planet! Radio images made from VLBI observations soon revealed that the sources at the centers of radio galaxies are “microscopic” by galaxy standards, even smaller than the distance between the sun and our nearest star.

When astronomers calculated the energy needed to power radio lobes they were astounded. It required 10 million stars to be “vaporized,” totally converting their mass to energy using Einstein’s famous equation E = mc2! Nuclear reactions, which power stars, cannot even convert 1 percent of a star’s mass to energy. So trying to explain the energy in radio lobes with nuclear power would require more than 1 billion stars, and these stars would have to live within the “microscopic” volume indicated by the VLBI observations. Because of these findings, astronomers began considering alternative energy sources: supermassive black holes.

We’ve also been tracing the orbits of planets, stars, and other objects that do give off conventional light. All this tracks back to suggest the supermassive black holes that Laplace et al first theorized about hundreds of years ago.

So, we knew what we were looking for. That’s how we were able to find it. And boom! Now we’ve got its photograph too. No more hiding from us, you goddamn light-devouring singularities. We’ve got your number.

Actually, Mercury Is Our Closest Planetary Neighbor

posted by Jason Kottke   Mar 21, 2019

If you look at the orbits of the planets adjacent to the Earth’s orbit (Venus & Mars), you’ll see that Venus’s orbit is closest to our own. That is, at its closest approach, Venus gets closer to Earth than any other planet. But what about the average distance?

According to this article in Physics Today by Tom Stockman, Gabriel Monroe, and Samuel Cordner, if you run a simulation and do a proper calculation, you’ll find that Mercury, and not Venus or Mars, is Earth’s closest neighbor on average (and spends more time as Earth’s closest neighbor than any other planet):

Although it feels intuitive that the average distance between every point on two concentric ellipses would be the difference in their radii, in reality that difference determines only the average distance of the ellipses’ closest points. Indeed, when Earth and Venus are at their closest approach, their separation is roughly 0.28 AU — no other planet gets nearer to Earth. But just as often, the two planets are at their most distant, when Venus is on the side of the Sun opposite Earth, 1.72 AU away. We can improve the flawed calculation by averaging the distances of closest and farthest approach (resulting in an average distance of 1 AU between Earth and Venus), but finding the true solution requires a bit more effort.

What the calculation also shows is that Mercury is the closest planetary neighbor to every planet, on average. Also, the authors of the paper don’t explicitly mention this, but the Sun (at 1 AU) is closer on average to the Earth than even Mercury (1.04 AU).

Video of a Japanese Space Probe Touching Down on an Asteroid

posted by Jason Kottke   Mar 05, 2019

In this video released by JAXA, the Japanese space agency, you can see an on-board view of the Hayabusa2 probe touching down on an asteroid called Ryugu.

The blast you see is the probe firing a bullet made of tantalum at the surface in order to collect a sample. Here’s a photo of the landing site. From Wikipedia:

When the sampler horn attached to Hayabusa2’s underside touched the surface, a projectile (5-gram tantalum bullet) was fired at 300 m/s into the surface. The resulting ejecta particles were collected by a catcher at the top of the horn, which the ejecta reaches under their own momentum under microgravity conditions.

This is the first of three samples that are scheduled to be collected by Hayabusa2. The third sampling will try to collect material located under the surface of the asteroid. To achieve this, a separate gun will detach from the probe and fire a copper bullet at the surface, blasting a hole in the surface and exposing “pristine material”. Meanwhile, the probe itself will deploy a separate camera to watch the bullet’s impact, scoot out of the way to avoid debris, and then come back in a couple of weeks to collect a sample from the resulting crater, which will then be returned to Earth along with the other two samples. Ingenious! I love it when a plan comes together!

Goodbye Opportunity, the Little Mars Rover that Could

posted by Jason Kottke   Feb 14, 2019

Yesterday, NASA declared the official end to the Opportunity rover mission on Mars.

One of the most successful and enduring feats of interplanetary exploration, NASA’s Opportunity rover mission is at an end after almost 15 years exploring the surface of Mars and helping lay the groundwork for NASA’s return to the Red Planet.

The Opportunity rover stopped communicating with Earth when a severe Mars-wide dust storm blanketed its location in June 2018. After more than a thousand commands to restore contact, engineers in the Space Flight Operations Facility at NASA’s Jet Propulsion Laboratory (JPL) made their last attempt to revive Opportunity Tuesday, to no avail. The solar-powered rover’s final communication was received June 10.

Opportunity was the longest-lived robot ever sent to another planet; it lasted longer than anyone could have imagined.

Designed to last just 90 Martian days and travel 1,100 yards (1,000 meters), Opportunity vastly surpassed all expectations in its endurance, scientific value and longevity. In addition to exceeding its life expectancy by 60 times, the rover traveled more than 28 miles (45 kilometers) by the time it reached its most appropriate final resting spot on Mars — Perseverance Valley.

Here’s a quick video overview of the milestones of Opportunity’s mission:

The NY Times has a great interactive feature about the rover’s activities and achievements and XKCD has a tribute.

Xkcd Oppy

The Hoover Dam’s “Hidden” 26,000-Year Astronomical Monument

posted by Jason Kottke   Feb 13, 2019

There’s a little-known monument located at the site of the Hoover Dam that shows the progression of “North Stars” as the Earth moves through its 25,772-year change of rotational axis. Alexander Rose of the Long Now Foundation couldn’t find much public documentation related to this celestial map, so he did some research.

I now had some historical text and photos, but I was still missing a complete diagram of the plaza that would allow me to really understand it. I contacted the historian again, and she obtained permission from her superiors to release the actual building plans. I suspect that they generally don’t like to release technical plans of the dam for security reasons, but it seems they deemed my request a low security risk as the monument is not part of the structure of the dam. The historian sent me a tube full of large blueprints and a CD of the same prints already scanned. With this in hand I was finally able to re-construct the technical intent of the plaza and how it works.

In order to understand how the plaza marks the date of the dam’s construction in the nearly 26,000-year cycle of the earth’s precession, it is worth explaining what exactly axial precession is. In the simplest terms, it is the earth “wobbling” on its tilted axis like a gyroscope — but very, very slowly. This wobbling effectively moves what we see as the center point that stars appear to revolve around each evening.

Presently, this center point lies very close to the conveniently bright star Polaris. The reason we have historically paid so much attention to this celestial center, or North Star, is because it is the star that stays put all through the course of the night. Having this one fixed point in the sky is the foundation of all celestial navigation.

Here are some explanatory notes that Rose wrote over the blueprints of the monument showing how to read the map:

Hoover Celestial Map

Update: Wally Motloch has also done some significant research on this monument.