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kottke.org posts about astronomy

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

A Flyover of Europa

posted by Jason Kottke   Feb 11, 2019

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

posted by Jason Kottke   Jan 24, 2019

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!

posted by Jason Kottke   Jan 23, 2019

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 — 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 — they’re brighter, and have a bright fresh splash pattern around them — 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

posted by Jason Kottke   Jan 23, 2019

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 — “as more film cut together, it became apparent narration was not needed” — 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 — 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

posted by Jason Kottke   Dec 09, 2018

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

posted by Jason Kottke   Nov 27, 2018

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

posted by Jason Kottke   Nov 26, 2018

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 — the name is a compression of Interior Exploration Using Seismic Investigations, Geodesy and Heat Transport — 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

posted by Jason Kottke   Nov 15, 2018

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 — 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

posted by Jason Kottke   Oct 11, 2018

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

posted by Jason Kottke   Oct 09, 2018

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

posted by Jason Kottke   Aug 31, 2018

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

posted by Jason Kottke   Jul 31, 2018

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 — almost three percent of the speed of light.

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

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

posted by Jason Kottke   Jul 30, 2018

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.

New Science from Jupiter

posted by Patrick Tanguay   May 03, 2018

Since Juno’s 2016 arrival in orbit of Jupiter, we’ve been marvelling at the pictures of the astonishing cloud formations and colours. This week NASA released a new video, explaining some of what they are discovering or hypothesizing about the internal systems and working of the planet.

What’s striking about Jupiter’s polar storms is that there are actually multiple cyclones at each pole. So instead of having one polar vortex like Earth, Jupiter was observed to have as many as eight giant swirls moving simultaneously on its north pole and as many as five on its south pole.

Liquid metallic hydrogen!

Deep inside Jupiter, high temperatures and crushing pressures transform Jupiter’s copious supplies of gaseous molecular hydrogen into an exotic form of matter known as liquid metallic hydrogen. Think of it as a mashup of atomic nuclei in a sea of electrons freely moving about. Jupiter’s powerful magnetic field almost certainly springs from dynamo action in Jupiter’s interior, the process by which the motion of this electrically-conducting fluid is converted into magnetic energy. The exact location within the interior is a mystery that researchers are still working to solve.

Self-generated auroras.

Jupiter’s magnetic field is home to the biggest and most powerful auroras in the solar system. Unlike Earth, which lights up in response to solar activity, Jupiter makes its own auroras. It does this by tapping into power generated by its own spinning magnetic field. Induced electric fields accelerate particles toward Jupiter’s poles where the aurora action takes place.

Recent results from Juno’s Gravity experiment show that Jupiter’s iconic belts and zones rotate as a series of cylinders down to depths of about 3000-5000 km. Beneath this depth, it appears that Jupiter may be rotating as a rigid body.

Clouds of Jupiter

Clouds of Jupiter

A high-resolution tour of the Moon from NASA

posted by Jason Kottke   Apr 09, 2018

Using imagery and data that the Lunar Reconnaissance Orbiter spacecraft has collected since 2009, NASA made this video tour of the Moon in 4K resolution. This looked incredible on my iMac screen.

As the visualization moves around the near side, far side, north and south poles, we highlight interesting features, sites, and information gathered on the lunar terrain.

See also The 100-megapixel Moon and A full rotation of the Moon.

“Oh my god!” People’s reactions to looking at the Moon through a telescope.

posted by Jason Kottke   Mar 15, 2018

Wylie Overstreet and Alex Gorosh took a telescope around the streets of LA and invited people to look at the Moon through it. Watching people’s reactions to seeing such a closeup view of the Moon with their own eyes, perhaps for the first time, is really amazing.

Whoa, that looks like that’s right down the street, man!

I often wonder what the effect is of most Americans not being able to see the night sky on a regular basis. As Sriram Murali says:

The night skies remind us of our place in the Universe. Imagine if we lived under skies full of stars. That reminder we are a tiny part of this cosmos, the awe and a special connection with this remarkable world would make us much better beings — more thoughtful, inquisitive, empathetic, kind and caring. Imagine kids growing up passionate about astronomy looking for answers and how advanced humankind would be, how connected and caring we’d feel with one another, how noble and adventurous we’d be.

Gorgeous 8K video of the aurora borealis dancing in the skies during a lunar eclipse

posted by Jason Kottke   Mar 14, 2018

8K resolution. Time lapse. 360º view. Aurora borealis. Lunar eclipse. I’m not really sure how you could pack much more into this video. Probably best experienced with some sort of VR rig, but for those of us without access to such a thing, watching it several times on a large screen while dragging the view around is a more than adequate substitute. If seeing the aurora borealis in person wasn’t already on your bucket list, it is now. Dang. (via the kid should see this)

Flyover video of Jupiter’s Europa

posted by Jason Kottke   Feb 05, 2018

NASA engineer Kevin Gill stitched together images from two 1998 observations of Europa by the Galileo spacecraft to create this super smooth flyover video of the icy Jovian moon. The details:

Processed using low resolution color images (IR, Green, Violet) from March 29 1998 overlaying higher resolution unfiltered images taken September 26 1998. Map projected to Mercator, scale is approximately 225.7 meters per pixel, representing a span of about 1,500 kilometers.

A time lapse video where you can actually see the Crab Nebula expanding

posted by Jason Kottke   Feb 02, 2018

The Crab Nebula is the result of a supernova that happened 6,500 light years away from Earth. From our perspective, the supernova happened almost 1000 years ago, in July, 1054. Using a home-built telescope, amateur astronomer Detlef Hartmann took a photos of the Crab Nebula over a ten-year period and assembled them into a time lapse video of the nebula’s expansion. Even after a millennia and across all that distance, the expansion of the nebula is clearly visible. And why not, those gases are moving at a clip of 1400 kilometers per second (more than 3 million miles per hour or 0.5% the speed of light).

As Phil Plait notes, we’re used to seeing things in our solar system move in the skies, but far-away bodies? That’s just weeeeeird.

Sure, the Moon moves in the sky, and the planets around the Sun, but deep sky objects — stars, nebulae, galaxies — are so distant that any physical motion at all is incredibly difficult to detect. They may as well be frozen in time. Being able to see it… that’s astonishing.

Hartmann’s is not the first Crab Nebula animation; I also found animations using images from 2002 & 2012, 1973 & 2001, 1999 & 2012, and 1950 & 2000. Someone with an interest in astronomy and photo/video editing should put all these views together into one 68-year time lapse of the nebula’s expansion.

Photos from the Curiosity rover’s 2000 days on Mars

posted by Jason Kottke   Feb 01, 2018

Mars Curiosity Photos

Mars Curiosity Photos

Mars Curiosity Photos

NASA’s Curiosity rover has been on Mars for more than 2000 days now, and it has sent back over 460,000 images of the planet. Looking at them, it still boggles the mind that we can see the surface of another planet with such clarity, like we’re looking out the window at our front yard. Alan Taylor has collected a bunch of Curiosity’s photos from its mission, many of which look like holiday snapshots from the rover’s trip to the American Southwest.

Lost in Light: how light pollution obscures our view of the night sky

posted by Jason Kottke   Dec 27, 2017

Because of light pollution from urban areas, many people around the world don’t know what the night sky actually looks like. Sriram Murali made a video to illustrate light pollution levels by shooting the familiar constellation of Orion in locations around the US with different amounts of light pollution, from bright San Francisco to a state park in Utah with barely any light at all. In SF, about all you can see are the handful of stars that make up Orion’s belt, arms, and legs. But as the locations get darker, the sky explodes in detail and Orion is lost among the thousands of visible stars (and satellites if you look closely).

This video is a followup to one Murali made of the Milky Way in increasingly dark locations, which is even more dramatic:

But he did the second video with Orion as a reference because many people had no concept of what the Milky Way actually looks like because they’ve never seen it before. Murali explains why he thinks light pollution is a problem:

The night skies remind us of our place in the Universe. Imagine if we lived under skies full of stars. That reminder we are a tiny part of this cosmos, the awe and a special connection with this remarkable world would make us much better beings — more thoughtful, inquisitive, empathetic, kind and caring. Imagine kids growing up passionate about astronomy looking for answers and how advanced humankind would be, how connected and caring we’d feel with one another, how noble and adventurous we’d be.

The measurement scale for sky darkness is called the Bortle scale, as explained by David Owen in his wonderful piece in the New Yorker:

In Galileo’s time, nighttime skies all over the world would have merited the darkest Bortle ranking, Class 1. Today, the sky above New York City is Class 9, at the other extreme of the scale, and American suburban skies are typically Class 5, 6, or 7. The very darkest places in the continental United States today are almost never darker than Class 2, and are increasingly threatened. For someone standing on the North Rim of the Grand Canyon on a moonless night, the brightest feature of the sky is not the Milky Way but the glow of Las Vegas, a hundred and seventy-five miles away. To see skies truly comparable to those which Galileo knew, you would have to travel to such places as the Australian outback and the mountains of Peru.

Nicola Twilley and Geoff Manaugh interviewed Paul Bogard, author of a book on darkness about light pollution and the Bortle scale:

Twilley: It’s astonishing to read the description of a Bortle Class 1, where the Milky Way is actually capable of casting shadows!

Bogard: It is. There’s a statistic that I quote, which is that eight of every ten kids born in the United States today will never experience a sky dark enough to see the Milky Way. The Milky Way becomes visible at 3 or 4 on the Bortle scale. That’s not even down to a 1. One is pretty stringent. I’ve been in some really dark places that might not have qualified as a 1, just because there was a glow of a city way off in the distance, on the horizon. You can’t have any signs of artificial light to qualify as a Bortle Class 1.

A Bortle Class 1 is so dark that it’s bright. That’s the great thing — the darker it gets, if it’s clear, the brighter the night is. That’s something we never see either, because it’s so artificially bright in all the places we live. We never see the natural light of the night sky.

If you’d like to find a place near you with less light pollution, check out The Light Pollution Map. I’m lucky enough to live in a place with a Bortle class of 3 and I’ve visited class 2 locations before…visiting one of the class 1 parks out west is definitely on my bucket list.

The 2017 Hubble Space Telescope Advent Calendar

posted by Jason Kottke   Dec 11, 2017

Hubble Advent 2017

From Alan Taylor at In Focus, the 10th anniversary installment of the Hubble Space Telescope Advent Calendar. One image taken by the Hubble for each day in December leading up to Dec 25th. Here’s Taylor’s caption for the image above:

A Caterpillar in the Carina Nebula. Scattered across the enormous Carina nebula are numerous dense clumps of cosmic gas and dust called Bok globules, including this one, which resembles a huge glowing caterpillar. First described by by astronomer Bart Bok, the globules are relatively small, dark, and cold regions made up of molecular hydrogen, carbon oxides, helium, and dust. The glowing edge of the caterpillar indicates that it is being photoionized by the hottest stars in the surrounding cluster. It has been hypothesized that stars may form inside these dusty cocoons.

Voyager 1 just fired its trajectory thrusters for the first time since 1980

posted by Jason Kottke   Dec 04, 2017

Nasa Voyager

The last time that the four trajectory thrusters on the Voyager 1 probe were fired, Jimmy Carter was still President of the United States. But with the main attitude control thrusters deteriorating from trying to keep the probe oriented correctly, the team thought they could keep the mission going using the trajectory thrusters. So they fired them up.

On Tuesday, Nov. 28, 2017, Voyager engineers fired up the four TCM thrusters for the first time in 37 years and tested their ability to orient the spacecraft using 10-millisecond pulses. The team waited eagerly as the test results traveled through space, taking 19 hours and 35 minutes to reach an antenna in Goldstone, California, that is part of NASA’s Deep Space Network.

Lo and behold, on Wednesday, Nov. 29, they learned the TCM thrusters worked perfectly — and just as well as the attitude control thrusters.

Voyager 1 was launched in 1977, is currently more than 13 billion miles from Earth, and is still functional and doing science. Incredible.

The first asteroid from outside our solar system pays us a visit

posted by Jason Kottke   Nov 21, 2017

Asteroid Oumuamua

Back in October, the solar system welcomed a visitor from interstellar space…the first interstellar asteroid ever detected.

Astronomers have confirmed that an object that recently passed by our planet is from outside our Solar System — the first interstellar asteroid that’s ever been observed. And it doesn’t look like any object we’ve ever seen in our cosmic neighborhood before.

Follow-up observations, detailed today in Nature, have found that the asteroid is dark and reddish, similar to the objects in the outer Solar System. It doesn’t have any gas or dust surrounding it, like comets do, and it’s stretched long and skinny, looking a bit like an oddly shaped pen. It’s thought to be about a quarter-mile long, and about 10 times longer than it is wide. That makes it unlike any asteroids seen in our Solar System, none of which are so elongated.

Here’s a video of the asteroid’s path through the solar system:

Um, folks…that looks like a rocket. How do we know this “asteroid” isn’t actually an ancient alien ship that’s become encrusted with rock over millions of years? Or an ancient weapon gone awry? We’ve all seen the first Star Trek movie, right? (I am only a little bit kidding about this.)

Update: Scientists — or at least one scientist who has a billionaire’s ear — think that’s there’s something a little odd about Oumuamua, so they’re going to check it for radio signals. Spoiler: they’re not going to find any, but wouldn’t it be fun if they did!?

Update: They listened and did not find any radio signals coming from Oumuamua.

Update: As of October 2018, here’s what we know about Oumuamua.

A few months later, another collaboration found that ‘Oumuamua wasn’t just being pulled by the sun’s gravity. Instead, it was being slightly accelerated by an unseen force, which they argued could only be attributed to comet “outgassing” acting like a thruster. With this additional information, the case appeared to be closed. “Interstellar asteroid is really a comet,” read the headline of a press release put out by the European Space Agency.

Gorgeous computer-generated animation of a nebula

posted by Jason Kottke   Nov 07, 2017

Designed by Teun van der Zalm, Nebulae is a computer generated nebula set to atmospheric music by Lee Rosevere. Worth seeking out a large screen for viewing. Several of van der Zalm’s other videos are equally beautiful variations on the same theme.