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kottke.org posts about astronomy

A Solar Eclipse from the Edge of Space

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 β€” high enough to see the blackness of space and Earth’s curvature β€” to take a 360Β° 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 360Β° 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

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

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 Β°F in 2.8 billion years). Toasty!↩


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

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

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

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

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 β€” 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

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

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 β€” it’s too rocky and full of craters β€” 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 β€” you can see that video here β€” 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

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 β€” 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

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)

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

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 galaxiesβ€”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

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 β€” 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

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

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 β€” 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

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 β€” 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.


A Flyover of Europa

Using recently processed data from the Galileo probe, NASA-JPL software engineer Kevin Gill created this low-altitude flyover of Europa, one of Jupiter’s moons.

The surface was imaged between 1996 & 1998 and is made up of a water-ice crust. Despite the cracks and streaks that you can see in the video, Europa actually has the smoothest surface of any object in the solar system.

These images are not super high-res because they were taken with equipment designed and built in the 80s. But we’re going to get a better look at Europa soon…both ESA’s JUICE probe and NASA’s Europa Clipper are planning on imaging the moon in the next decade.


Visualizing the Speed of Light

Light is fast! In a recent series of animations, planetary scientist James O’Donoghue demonstrates just how fast light is…and also how far away even our closest celestial neighbors are. Light, moving at 186,000 mi/sec, can circle the Earth 7.5 times per second and here’s what that looks like:

It can also travel from the surface of the Earth to the surface of the Moon in ~1.3 seconds, like so:

That seems both really fast and not that fast somehow. Now check out light traveling the 34 million miles to Mars in a pokey 3 minutes:

And Mars is close! If O’Donoghue made a real-time animation of light traveling to Pluto, the video would last over 5 hours. The animation for the closest undisputed galaxy, Seque 1, would last 75,000 years and 2.5 million years for the Andromeda galaxy animation. The farthest-known objects from Earth are more than 13 billion light years away. Light is slow!

See also The Leisurely Pace of Light Speed.


Video: A Meteorite Hit the Moon During the Recent Eclipse!

Something incredible happened during the super blood wolf moon eclipse that took place on Sunday night: a meteorite struck the moon during the eclipse and it was captured on video, the first time this has ever happened.

Jose Maria Madiedo at the University of Huelva in Spain has confirmed that the impact is genuine. For years, he and his colleagues have been hoping to observe a meteorite impact on the moon during a lunar eclipse, but the brightness of these events can make that very difficult β€” lunar meteorite impacts have been filmed before, but not during an eclipse.

The 4K video of the impact above was taken by amateur astronomer Deep Sky Dude in Texas…he notes the impact happening at 10:41pm CST. I couldn’t find any confirmation on this, but the impact looks bright enough that it may have been visible with the naked eye if you were paying sufficient attention to the right area at the right time.

Phil Plait has a bunch more info on the impact. If the impact site can be accurately determined, NASA will attempt to send the Lunar Reconnaissance Orbiter to get photos of it.

Interestingly, I talked to Noah Petro, Project Scientist for LRO, and he noted that the impact may have created secondary craters, smaller ones made by debris blown out by the main impact. Those will spread out over a larger area, and are easier to spot, so it’s possible that even with a rough location known beforehand the crater can be found. Also, fresh craters look distinct from older ones β€” they’re brighter, and have a bright fresh splash pattern around them β€” so once it’s in LRO’s sights it should be relatively easy to spot.

It’s not clear how big the crater will be. I’ve seen some estimates that the rock that hit was probably no more than a dozen kilograms or so, and the crater will be probably 10 meters across. That’s small, but hopefully its freshness will make it stand out.


Universe, a Short Documentary from 1960 that Inspired Kubrick’s 2001

In 1960, the National Film Board of Canada released a short documentary called Universe. The film follows the work of astronomer Donald MacRae at an observatory in Ontario, which is accompanied a special effects-heavy tour of the solar system, galaxy, and universe: “a vast, awe-inspiring picture of the universe as it would appear to a voyager through space”. Universe was nominated for an Oscar in 1961 and also caught the eye of Stanley Kubrick, who used it as inspiration for 2001: A Space Odyssey.

“Stanley had seen the National Film Board movie Universe.” Most of the crew on 2001 were familiar with the Canadian production, made by filmmakers Colin Low and Roman Kroitor, all having seen it at the early stages of 2001’s production, it being “required watching” at the insistence of Kubrick himself, who had seen the documentary “almost 100 times”, “until the sprockets wore out,” 2001 special effects supervisor Con Pedersen remembers.

Kubrick was so taken by the depiction of the celestial objects in the film that he hired the co-director and a special effects technician from Universe to work on 2001. The narrator of Universe, Douglas Rain, also became a integral part of Kubrick’s masterpiece. After ditching the idea that 2001 would be narrated by Rain β€” “as more film cut together, it became apparent narration was not needed” β€” Kubrick chose Rain as the now-iconic voice of HAL 9000.

After finally excising the narrator altogether, he simply made Rain the voice of HAL, liking his “bland mid-Atlantic accent”. The decision was entirely Kubrick’s, who had become concerned with the character of the computer. “Kubrick was having,” Rain says, “a problem with the computer. ‘I think I made him too emotional and too human,’ he said. ‘I’m having trouble with what I’ve got in the can. Would you consider doing his voice?’ So we decided on the voice of the computer.”

But back to Universe, which is a marvelous little film (even though it asserts at one point that “it is reasonably certain” that Mars contains vegetation). I love the early sequence of the astronomer setting up his telescope β€” the way he walks along inside of it and then casually lifts it up into place. It’s really just a bigger version of the small reflector that I have, not any more complicated than a couple of mirrors pointed in the right direction. It’s incredible what we humans have learned about the universe simply by collecting ancient starshine with polished lenses and mirrors. (via clayton cubitt)


Hear the First Sounds Ever Recorded on Mars

NASA’s InSight mission recently landed on Mars and like other missions before it, the lander is a equipped with a camera and has sent back some pictures of the red planet. But InSight is also carrying a couple of instruments that made it possible to record something no human has ever experienced: what Mars sounds like:

InSight’s air pressure sensor recording the sound of the wind directly and the seismometer recorded the sounds of the lander’s solar panels vibrating as Martian winds blew across them.

Two very sensitive sensors on the spacecraft detected these wind vibrations: an air pressure sensor inside the lander and a seismometer sitting on the lander’s deck, awaiting deployment by InSight’s robotic arm. The two instruments recorded the wind noise in different ways. The air pressure sensor, part of the Auxiliary Payload Sensor Subsystem (APSS), which will collect meteorological data, recorded these air vibrations directly. The seismometer recorded lander vibrations caused by the wind moving over the spacecraft’s solar panels, which are each 7 feet (2.2 meters) in diameter and stick out from the sides of the lander like a giant pair of ears.

The sounds are best heard with a good pair of headphones.


If the Planets Were As Close As the Moon

Using 3D rendering software, Yeti Dynamics made this video that shows what our sky would look like if several of our solar system’s planets orbited the Earth in place of the Moon. If you look closely when Saturn and Jupiter are in the sky, you can see their moons as well.

the moon that flies in front of Saturn is Tethys. It is Tiny. but *very* close. Dione would be on a collision course, it’s orbital distance from Saturn is Nearly identical to our Moon’s orbit around Earth

See also their video of what the Moon would look like if it orbited the Earth at the same distance as the International Space Station.

Update: And here’s what it would look like if the Earth had Saturn’s rings. (via @FormingWorship)


Watch It Live: NASA’s InSight Probe Lands on Mars Today

After a seven-month journey covering over 300 million miles, NASA’s InSight probe will land on the surface of Mars today around 3pm. The video embedded above is a live stream of mission control at NASA’s Jet Propulsion Laboratory that starts at 2pm and will be the best thing to watch as the probe lands. (See also this live stream of NASA TV.) The landing will occur around 2:47pm ET but the landing signal from Mars won’t arrive on Earth until 2:54pm ET at the earliest. And no video from the landing itself of course…”live” is a bit of a misnomer here but it still should be exciting.

NASA produced this short video that shows what’s involved in the landing process, aka how the probe goes from doing 13,000 mph to resting on the surface in just six-and-a-half minutes.

The NY Times has a good explainer on the InSight mission and landing.

NASA’s study of Mars has focused on the planet’s surface and the possibility of life early in its history. By contrast, the InSight mission β€” the name is a compression of Interior Exploration Using Seismic Investigations, Geodesy and Heat Transport β€” will study the mysteries of the planet’s deep interior, aiming to answer geophysical questions about its structure, composition and how it formed.

I love this stuff…the kids and I will be watching for sure!

Update: The Oatmeal has a great comic about the InSight landing.


Art on the Moon

The NY times recently asked eight artists what art projects they would do if they could fly to the Moon. Here’s Kara Walker’s answer:

Gil Scott Heron wrote that famous poem, “Whitey on the Moon”: “The man just upped my rent last night / Cause whitey’s on the moon / No hot water, no toilets, no lights / But whitey’s on the moon.”

I got thinking about a moon colony, which plenty of people have talked about pretty seriously over the years. So what I’d do is this: For every female child born on Earth, one sexist, white supremacist adult male would be shipped to the moon. They could colonize it to their heart’s content, and look down from a distance of a quarter-million miles. It’s a monochrome world up there; probably they’d love it. The colony would be hermetically sealed. And the rest of us could enjoy the sight of them from a safe distance. Maybe there could be some kind of selection ritual involved, something to do with menstruation and the tides β€” a touch of nature, to add a bit of irony justice to the endeavor.

For the supremacists, maybe traveling so far from home would help inspire a different worldview. And for the rest of us down on Earth, perhaps this is an opportunity to focus on the nature of our home planet with the same dreamy reverence we once reserved for the moon.

Here’s Scott-Heron’s Whitey on the Moon. In contrast, architect Daniel Libeskind would turn the Moon into a square by painting part of it black:

My son Noam is an astrophysicist at the Leibniz Institute in Germany, and we did some calculations about how it could work. We thought the best way would be to paint sections of it black, so they no longer reflect the sun’s light. To account for the curvature, you’d need to paint four spherical caps on the moon’s surface. That would create a kind of frame that looks square when you see it from earth.


Fly Me to the Moonmoon

Moonmoon

In a paper called “Can Moons Have Moons?”, a pair of astronomers says that some of the solar system’s moons, including ours, are large enough and far enough away from their host planets to have their own sizable moons.

We find that 10 km-scale submoons can only survive around large (1000 km-scale) moons on wide-separation orbits. Tidal dissipation destabilizes the orbits of submoons around moons that are small or too close to their host planet; this is the case for most of the Solar System’s moons. A handful of known moons are, however, capable of hosting long-lived submoons: Saturn’s moons Titan and Iapetus, Jupiter’s moon Callisto, and Earth’s Moon.

Throughout the paper, the authors refer to these possible moons of moons as “submoons” but a much more compelling name has been put forward: “moonmoons”.

Moonmoon is an example of the linguistic process of reduplication, which is often deployed in English to make things more cute and whimsical. In the pure form of reduplication, you get words like bonbon, choo-choo, bye-bye, there there, and moonmoon but relaxing the rules a little to incorporate rhymes and near-rhymes yields hip-hop, zig-zag, fancy-shmancy, super-duper, pitter-patter, and okey-dokey. And with contrastive reduplication, in which a word repeats as a modifier to itself:

“It’s tuna salad, not salad-salad.”
“Does she like me or like-like me?”
“The party is fancy but not fancy-fancy.”
“The car isn’t mine-mine, it’s my mom’s.”

Fun! And astronomy should be fun too. Let’s definitely call them moonmoons.


Earth-Sized Telescope Aims to Snap a Photo of Our Galactic Black Hole

Astronomers behind the Event Horizon Telescope are building a virtual telescope with a diameter of the Earth to photograph the supermassive black hole at the center of our galaxy. The idea is that different observatories from all over the surface of the Earth all look at the black hole at the same time and the resulting data is stitched together by a supercomputer into a coherent picture. Seth Fletcher wrote a great piece about the effort for the NY Times Magazine (it’s an excerpt from his new book, Einstein’s Shadow: A Black Hole, a Band of Astronomers, and the Quest to See the Unseeable):

Astronomical images have a way of putting terrestrial concerns in perspective. Headlines may portend the collapse of Western civilization, but the black hole doesn’t care. It has been there for most of cosmic history; it will witness the death of the universe. In a time of lies, a picture of our own private black hole would be something true. The effort to get that picture speaks well of our species: a bunch of people around the world defying international discord and general ascendant stupidity in unified pursuit of a gloriously esoteric goal. And in these dark days, it’s only fitting that the object of this pursuit is the darkest thing imaginable.

Avery Broderick, a theoretical astrophysicist who works with the Event Horizon Telescope, said in 2014 that the first picture of a black hole could be just as important as “Pale Blue Dot,” the 1990 photo of Earth that the space probe Voyager took from the rings of Saturn, in which our planet is an insignificant speck in a vast vacuum. A new picture, Avery thought, of one of nature’s purest embodiments of chaos and existential unease would have a different message: It would say, There are monsters out there.

A video by the EHT team says that imaging the black hole is like trying to count the dimples on a golf ball located in LA while standing in NYC.

EHT team member Katie Bouman also did a TEDx talk on the project.

P.S. There’s a cloud near the center of the galaxy that tastes like raspberries and smells like rum.


Stunning high-res photo of a stellar nursery

Carina Nebula

Astronomers using an infrared telescope at the European Southern Observatory in Chile recently released an infrared photo of the Carina Nebula that shows the inner workings of the star factory “as never before”.

This spectacular image of the Carina nebula reveals the dynamic cloud of interstellar matter and thinly spread gas and dust as never before. The massive stars in the interior of this cosmic bubble emit intense radiation that causes the surrounding gas to glow. By contrast, other regions of the nebula contain dark pillars of dust cloaking newborn stars.

This is a massive image…the original is 140 megapixels (<- that’s a 344MB download). Phil Plait notes that it may contain about 1 million stars and gives a bit of background on what we’re looking at here:

The colors you see here are not what you’d see with your eye, since it’s all infrared. What’s shown as blue is actually 0.88 microns, or a wavelength just outside what your eye can see. Green is really 1.25 microns and red is 2.15, so both are well into the near-infrared.

Even in the infrared, a lot of gas and dust still are visible. That’s because there’s a whole bunch of it here. And it’s not just randomly strewn around; patterns are there when you look for them.

For example, in this subimage you can see long, skinny triangles of dust. These are formed when very thick clots of dust are near very luminous stars. The wind and fierce blast of ultraviolet light from the stars erode away at the clump and also flow around it. They’re like sandbars in a stream! This is the same mechanism that made the Pillars of Creation in the Eagle nebula, and they’re common in star-forming nebulae.


A 20-year time lapse of stars orbiting a massive black hole

The European Southern Observatory’s Very Large Telescope in Chile has been watching the supermassive black hole in the center of our galaxy and the stars that orbit it. Using observations from the past 20 years, the ESO made this time lapse video of the stars orbiting the black hole, which has the mass of four million suns. I’ve watched this video like 20 times today, my mind blown at being able to observe the motion of these massive objects from such a distance.

The VLT was also able to track the motion of one of these stars and confirm for the first time a prediction made by Einstein’s theory of general relativity.

New infrared observations from the exquisitely sensitive GRAVITY, SINFONI and NACO instruments on ESO’s Very Large Telescope (VLT) have now allowed astronomers to follow one of these stars, called S2, as it passed very close to the black hole during May 2018. At the closest point this star was at a distance of less than 20 billion kilometres from the black hole and moving at a speed in excess of 25 million kilometres per hour β€” almost three percent of the speed of light.

S2 has the mass of about 15 suns. That’s 6.6 Γ— 10^31 pounds moving at 3% of the speed of light. Wowowow.


Moon 101, a quick explainer video from National Geographic about the Moon

I have been going a little Moon crazy lately. There was the whole Apollo 11 thing, I finished listening to the excellent audiobook of Andrew Chaikin’s A Man on the Moon (which made me feel sad for a lot of different reasons), and am thinking about a rewatch of From the Earth to the Moon, the 1998 HBO series based on Chaikin’s book. This video from National Geographic answers a lot of questions about the Moon in a short amount of time.