Major Cryovolcanic Eruption on a Comet

Nov. 25, 2022: The British Astronomical Association (BAA) is reporting a new outburst of cryovolcanic comet 29P/Schwassmann-Wachmann. On Nov. 22nd, the comet’s nucleus suddenly brightened by more than 4 magnitudes–a sign that a major eruption was underway. Cryomagmatic debris is now expanding in a shell shaped like Pac-Man:

Cai Stoddard-Jones took the picture on Nov. 23rd using the Faulkes Telescope North in Hawaii. At the time, the shell was already more than 100,000 km in diameter.

The Pac-Man shape of the ejecta shows that this is not a uniform global eruption. Instead, it is coming from one or more discrete sources on the comet’s surface.

This fits a leading model of the comet developed by Dr. Richard Miles of the British Astronomical Association. Miles believes that 29P is festooned with ice volcanoes. There is no lava. The “magma” is a cold mixture of liquid hydrocarbons (e.g., CH4, C2H4, C2H6 and C3H8) akin to those found in lakes and streams on Saturn’s moon Titan. The comet’s cryomagma is suffused with dissolved gases N2 and CO, a bit like carbonation in a soda bottle. These bottled-up volatiles love to explode when a fissure is opened by the warming action of sunlight.

A new image taken on Nov. 25th by astronomers André Debackère and M. Malaric adds weight to the idea that a single volcano is driving the outburst. Processing the data with a rotational gradient filter, Debackère found a bright plume of debris at position angle 330 degrees (the 1 o’clock position):

This narrow plume probably leads back to the primary source the eruption. Currently streaming away from the nucleus at 75 m/s (270 km/hr), the plume stretches more than 11,000 km into space. If an eruption like this were happening on Earth, it would be plastering thousands of satellites with frosty hydrocarbons.

The integrated brightness of the comet (magnitude +11), puts it within easy reach of many backyard telescopes. Pac-Man already subtends an angle wider than Mars and, if past eruptions are any guide, it should grow much larger in the nights ahead. Observers can find 29P after sunset in the constellation Gemini.

For more information visit the British Astronomical Association’s MISSION 29P website.

more images: from Tom Gwilym of Sturgeon Bay, Wisconsin;

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A Small Asteroid Just Hit Earth. Astronomers Saw it Coming

Nov. 19, 2022: Astronomers are getting better at this. Today, for the 6th time in recent history, an Earth-bound asteroid was discovered before it hit Earth. Astronomer David Rankin was conducting a routine survey at Mt Lemmon, Arizona, on Nov. 19th when he spotted the 0.7-meter space rock coming in from the asteroid belt. Three hours later it was blazing through the atmosphere above Canada:

Dereck Bowen photographed the Moon-bright fireball (above) from his backyard in Brantford, Ontario. “It was a lucky shot,” he says. “I had my GoPro set up trying to get some action from the Leonid meteor shower, and I was astonished to find the asteroid.”

Not everyone was surprised. Rankin’s discovery triggered warnings of an imminent impact. According to the Minor Planet Center, seven observatories had time to photograph the sub-meter object before it hit on Nov. 19th at 08:27 UTC. This is a testament to astronomers’ improving ability to catch incoming dangers from space.

After the asteroid entered the atmosphere, ground-based weather radars tracked pieces of the disintegrating space rock as far down as 850 meters above Earth’s surface. It was a deep hit, and meteorites may have reached the ground east of Grimsby, Ontario. NASA created this map of the fall zone:

Above: Colored polygons estimate the landing sites of meteorites from ~1g (yellow) to 10kg (red) [more maps] Credit:NASA/ARES

Most of the fall landed in Lake Ontario but small masses might be found east of Grimsby with larger masses near McNab, according to NASA’s Astromaterials Research and Exploration Science Division. If you find a piece, here’s how to handle it.

More than 50 eyewitness reports of the fireball have been submitted to the American Meteor Society from as far south as Maryland in the USA. Experienced observers say the fireball’s peak brightness was between magnitude -10 and -20. For some people the fireball was brighter than a full Moon.

The Minor Planet Center has posthumously designated this asteroid 2022 WJ1.

For the record, previous asteroids detected just before they hit Earth are: 2008 TC3, 2014 AA, 2018 LA, 2019 MO, and 2022 EB5. There have been two this year alone!

more images: from Brian Curtis of Sault Ste Marie, Michigan

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Why Do Russian Rockets Make Blue Auroras?

Nov. 15, 2022: On Nov. 3rd, 2022, sky watchers in Sweden and Norway watched a strange blue aurora snake across the night sky. Its color and motion seemed to defy the normal laws of aurora physics. Indeed, it was not an aurora. Experts quickly realized that the display coincided with the launch of an ICBM from a Russian submarine beneath the White Sea.

It wasn’t the first time blue clouds have appeared. On Dec. 9, 2009, a Russian rocket caused a worldwide sensation when it created a blue spiral over Norway. “Blue auroras” appeared again on Oct. 26, 2017, following another Russian battle drill:

The blue exhaust of a Russian rocket on Oct. 26, 2017. Credit: Alexey Yakovlev of Strezhevoy, Russia

Over the years, Arctic sky watchers have seen many of these blue clouds, with explanations ranging from auroras to aliens to wormholes in space. In fact, rockets are the most likely explanation. Common threads seem to be the involvement of Bulava and Topol missiles, and the use of solid propellant ascent motors.

A paper published in 2016, “Exceptional optical phenomena observed during the operation of Russian launchers,” explains how such rockets might produce blue lights:

“A major combustion product of the solid fuel is aluminum oxide Al2O3 (~40% by mass),” the authors write. “At high temperatures, the formation of aluminum monoxide, AlO, also occurs. AlO exists in a gaseous state. Resonant scattering of sunlight by these molecules causes the luminescence in the wavelength region 4374–5424 Ǻ, which corresponds to the turquoise color of the gas-dust trail of the rocket.”

Mystery solved? Probably. But that doesn’t mean we don’t want to investigate further. Arctic sky watchers, if you see any future “blue auroras,” submit your photos here.

Mysterious Blue Auroras

Nov. 3, 2022: Thursday night (Nov. 3rd) in Sweden, sky watchers were puzzled when a strange ribbon of blue light appeared during a geomagnetic storm. “It didn’t look like any auroras I have ever seen before,” says Chad Blakley, the director of Lights over Lapland. One of his tour guides, Miquel Such, video-recorded the phenomenon:

A G1-class geomagnetic storm was underway on Nov. 3rd when the blue ribbon appeared. Webcams saw it first at 1615 UT (5:15 p.m. local Abisko time). It rapidly brightened to naked-eye visibility, then sank below the horizon 30 minutes later. The whole time, regular green auroras danced around and seemingly in front of it: movie.

But what was it?

Space physicist Toshi Nishimura of Boston University took a look at the video. “It looks really odd if it’s aurora,” he says. “One auroral arc shouldn’t cut across another auroral arc without disturbing it, so it’s hard to explain this from an auroral physics point of view.”

Above: The blue ribbon over Lake Tornetrask. Photo credit: Claudio Comi

Another possibility is rocketry. Since late October Russia has been conducting ICBM firing exercises in the Barents Sea with the nuclear-powered missile cruiser “Peter the Great” in the area for combat training. Rocket exhaust has been known to create displays like this in the past.

However, no one saw a rocket. Multiple witnesses in Abisko agree that nothing streaked across the sky before the blue band appeared.

For now, the blue ribbon remains a mystery. Any photographers who caught it are encouraged to submit their images. Photos from different locations may help determine the height of the emission. And, of course, if anyone saw a rocket, let us know!

more images: from Hendrik Zwart of Sjøvegan, Salangen Kommune, Norway

MYSTERY SOLVED? On Nov. 3rd, Russia’s nuclear submarine Generalissimus Suvorov test-fired an ICBM from beneath the White Sea. This might be linked to a “blue aurora” widely seen from northern Sweden and Norway on the same date. The sightings are described below. The Russian military has issued a NOTAM (Notice to Airmen) for additional missile firings through Nov. 5th. Sky watchers in the area should remain alert for unusual auroras.

Circumstantial evidence is mounting that the blue apparition was, in fact, a Russian rocket. Back in October 2017 sky watchers across northern Scandinavia saw a similar display documented on It was caused by a Topol ICBM launched from the Plesetsk space center 800 km north of Moscow.

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BlueWalker 3 Sightings

Nov. 13, 2022: Evidence is mounting that AST SpaceMobile’s BlueWalker 3 satellite has unfurled its its huge antenna. Multiple observers have seen the satellite shining like a 1st magnitude star–a 50-fold increase in brightness compared to just a few days ago. Paul Maley of Arizona saw it in bright morning twilight on Nov. 11th, and Gary Dowdle of Texas caught it just before sunrise on Nov. 12th:

“The satellite was very low in the northeastern sky, about 16.5 degrees above the horizon,” says Dowdle. “Nevertheless, it was easily visible to the naked eye at magnitude +2 just below the handle of the Big Dipper.”

Paul Maley saw it again on Sunday morning, Nov. 13th. “It came out of Earth’s shadow at magnitude +3 then steadily brightened to magnitude +1,” he says. “Its visual profile remains unchanged over the last 3 days. The spacecraft appears completely stable with no signs of tumbling.”

BlueWalker 3 is a revolutionary communications satellite designed to provide cell phone service from space. To detect weak cell phone signals from Earth’s surface it needs a very large antenna. BlueWalker 3’s is about the size of a squash court:

Astronomers have worried that BlueWalker 3 could become one of the brightest objects in the night sky, reflecting bright beams of sunlight into telescopes on the ground below. Those fears have not been fully realized. If the satellite is really only as bright as a 1st magnitude star, then it would be no worse than, say, China’s Tiangong space station or the ISS.

It may be too soon to relax, though. While this is only a single satellite for now, Bluewalker’s maker AST SpaceMobile plans to launch more than 100 larger satellites called BlueBirds. These satellites could be more than twice the size of BlueWalker 3 and much brighter. Flocks of Bluebirds could ruin a lot of astronomical observations.

Set against this detriment to astronomy is the good these satellites could do by providing emergency services and cell phone connectivity to remote areas. AST SpaceMobile explains.

You can help monitor BlueWalker 3. Morning and evening flybys are currently happening over the USA. Check Heavens Above for local flyby times and let us know what you see.

UPDATE: The CEO of AST SpaceMobile confirmed in a Tweet this morning that BlueWalker 3 has indeed unfurled its antenna, accounting for the observations described below. He also shared images of the antenna taken from orbit with different sun angles.

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21 years Ago, A Severe Geomagnetic Storm

Nov. 6, 2022: It could happen again–and soon. Twenty-one years ago, a full-halo CME struck Earth’s magnetic field, sparking a severe G4-class geomagnetic storm. “Skies over Central Europe glowed bright red and violet,” recalls Heiko Ulbricht, who photographed the display from Saxony, Germany, on Nov. 6, 2001:

“The shock front hit the Earth’s magnetic field around 2 a.m. CET–good timing for sky watchers in Europe,” says Ulbricht. From there, auroras spread around the world, descending as far south as Florida, Texas, and California in the United States. The storm persisted for more than 24 hours.

The CME left the sun two days earlier, propelled by an X1-class solar flare from sunspot AR9684. SOHO coronagraph images of the CME were quickly overwhelmed by a “snowstorm” of energetic particles accelerated by shock waves in the approaching storm cloud:

The kind of explosion that produced this storm is, interestingly, not rare. Young Solar Cycle 25 has already produced 8 similar X-flares since 2021. None of the related CMEs delivered a direct hit, however.

“If you look at the sun today, it could definitely produce a spectacle of this kind again,” says Ulbricht. Browse the aurora gallery from 21 years ago to see what might be coming.

Nov. 6, 2001, Aurora Photo Gallery
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The Taurid Swarm is Coming

Oct. 31, 2022: Have you ever heard of the “Halloween Fireballs?” Astronomers call them Taurid meteors. They appear every year from late October through early November when Earth passes through a stream of debris associated with Comet 2P/Encke. Dan Bush photographed this Taurid exploding over Albany, Missouri:

“Fireball season has arrived,” says Bush. “I have caught many with my meteor camera system including this Taurid fireball above the clouds on Oct. 27th and another good one on Oct. 28th”

We’re about to see a lot more of these. Forecasters believe that a swarm of Taurid meteoroids is approaching Earth, and it could double the usual rate of fireballs–not only on Halloween, but also through the early weeks of November.

Taurid meteors are thought to be debris from a giant comet that broke apart in the inner Solar System 10 to 20 thousand years ago. The breakup produced a mixture of dust and larger bodies that are still present today. Comet 2P/Encke itself may be just one of the fragments.

Over the years, Jupiter’s gravity has shepherded some of these meteoroids into a well-defined cloud–the “Taurid Swarm.” It visits Earth every 3 or 7 years. Previous encounters with the Swarm in 2005 and 2015 produced showers of fireballs observed around the world. The last outburst was 7 years ago, which means 2022 should be a Swarm year, too.

In 1975 the Swarm contacted the Moon, making Apollo seismic sensors ring with evidence of objects hitting the lunar surface. If there’s a repeat strike this year, Nov. 8th might be a good time to look for it. The Moon’s surface will be darkened by Earth’s shadow during a total lunar eclipse, improving the visibility of any exploding lunar meteors.

Although the Taurid shower typically peaks on Nov. 5th, it is a broad maximum, weeks long. Any of the nights ahead could produce a Taurid display. Look up during the hours around midnight; you can expect to see a few fireballs per hour streaking from the horns of Taurus–and many more if the Swarm arrives.

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Powerful Gamma-Ray Burst Made Currents Flow in the Earth

Oct. 17, 2022: Astronomers have never seen anything quite like it. On Oct. 9, 2022, Earth-orbiting satellites detected the strongest gamma-ray burst (GRB) in modern history: GRB221009A. How strong was it? It caused electrical currents to flow through the surface of our planet. Dr. Andrew Klekociuk in Tasmania recorded the effect using an Earth Probe Antenna:

Note: Data from STIX have been flipped (increasing counts go down) to ease comparison of the two waveforms. NWC is a VLF transmitter in Australia.

The blue curve is a signal from Klekociuk’s antenna, which was sensing VLF (very low frequency) currents in the soil at the time of the blast. The orange curve shows the gamma-ray burst recorded by the high-energy STIX telescope on Europe’s Solar Orbiter spacecraft, one of many spacecraft that detected the event. The waveforms are a nearly perfect match.

“I am a climate scientist at the Australian Antarctic Division–that’s my day job,” says Klekociuk. “VLF is my hobby. I started doing VLF radio measurements in the 1970’s when I was in high school. This is the first time I have detected a gamma-ray burst.”

Klekociuk’s unusual “ham rig” uses Earth itself as a giant antenna. In his back garden there are two metal spikes stuck into the ground 75 meters apart. They are connected to a radio receiver via insulated buried wires. In recent years amateur radio operators have been experimenting with this weird kind of antenna to detect VLF radio signals circling our planet in the Earth-ionosphere waveguide. Earth’s crust forms one of the waveguide’s walls, allowing Earth Probe antennas to detect distant transmitters.

“During the gamma-ray burst I detected flickering from multiple stations,” says Klekociuk, who made this map showing transmission paths illuminated by the GRB:

NWC, VTX3, Mokpo and NML are VLF transmitters Klekociuk monitors using his Earth Probe Antenna. GRB effects were observed for all except NML, which was outside the radiation footprint.

Researchers have known since 1983 that gamma-ray bursts can ionize Earth’s atmosphere and, thus, disturb the great waveguide. This appears to be the first time anyone has recorded the effect using an Earth Probe Antenna.

The outburst on Oct. 9th shocked astronomers. Consider this tweet from Phil Evans of the University of Leicester in the immediate aftermath of the burst: “It’s bright. Really bright. Like, stupidly really bright.” Evans works with data from NASA’s Swift gamma-ray observatory, and the overflowing signal had apparently broken some of his plotting software.

Researchers have since pinpointed the burst. It came from a dusty galaxy 2.4 billion light years away, almost certainly triggered by a supernova explosion giving birth to a black hole. This is actually the closest GRB ever recorded, thus accounting for its extreme intensity.

The afterglow of GRB 221009A about an hour after it was first detected. Credit: NASA/Swift. [more]

“In our research group, we’ve been referring to this burst as the ‘BOAT’, or Brightest Of All Time, because when you look at the thousands of bursts gamma-ray telescopes have been detecting since the 1990s, this one stands apart,” says Jillian Rastinejad, an astronomer at Northwestern University who has been monitoring the burst’s afterglow using the Gemini South Telescope in Chile.

Meanwhile, other observers in the UK and Germany have also reported ionospheric disturbances resulting from the burst. They all used regular above-ground antennas.

2.4 billion light years away… Now that’s DXing.

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Lucy’s Super-Close Flyby on Earth

Oct. 15, 2022: Most spacecraft try to avoid hitting the atmosphere. Lucy is about to do it on purpose. On Oct. 16th, NASA’s Lucy spacecraft will skim Earth’s atmosphere, passing only 220 miles (350 kilometers) above our planet’s surface. Near closest approach over Australia it will be visible to the naked eye glowing almost as brightly as a 1st magnitude star.

This is a gravity assist maneuver–the first of three required for Lucy’s complicated mission to visit 8 different asteroids. The slingshot will give Lucy the energy it needs to fly towards the asteroid belt and, its ultimate destination, the orbit of Jupiter.

Named for a hominid fossil found in 1974 in Africa, Lucy is on a mission to study a completely different kind of relic: the Trojan asteroids. These are primitive leftovers from the formation of our solar system, collected into swarms around two of Jupiter’s Lagrange points. Sensors onboard the spacecraft will examine their appearance and composition, putting competing theories of planetary genesis to the test.

To reach the Trojans, Lucy must first return to Earth. Launched on Oct. 16, 2021, the spacecraft is coming home after exactly one year in space. Lucy’s trajectory will bring it deep into near Earth orbit, passing through a region full of Earth-orbiting satellites and debris. NASA will be ready to make last-minute adjustments to avoid collisions. The altitude is so low, the mission team had to include the effect of atmospheric drag when designing the flyby. Passing so close allows Lucy to extract maximum energy from Earth’s gravitational field.

On the left, the location in the sky where Lucy will first appear when it emerges from the Earth’s shadow for the Western United States. Red stars correspond to cities on the right.

Observers in western Australia will be the first to see Lucy. At around 10:55 UTC (6:55 p.m. local time) on Oct. 16th, the spacecraft will race overhead shining like a 1st or 2nd magnitude star. At the apex of its brightness, it will suddenly disappear into Earth’s shadow, vanishing at 11:02 UTC (7:02 p.m. local time).

Lucy will continue over the Pacific Ocean in darkness and emerge from the Earth’s shadow at 4:26 a.m. PDT (11:26 UTC). By that time it will have dimmed to 6th or 7th magnitude. Amateur astronomers in the western United States should be able to see Lucy using binoculars or a small telescope.

After the gravity assist, Lucy will recede from Earth, passing by the Moon and taking a few pictures before continuing out into interplanetary space. It might remain bright enough to see using backyard telescopes for more than 24 hours.

Want to see Lucy? You can spot the spacecraft using observing tips from the Southwest Research Institute. Ephemerides from JPL are recommended, too.

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Dramatic Ground-based Images of DART’s Asteroid Strike

Sept. 27, 2022: On Monday, Sept. 26th, NASA’s DART spacecraft hit asteroid Dimorphos. Surprising even NASA, ground-based telescopes had no trouble seeing the impact. Astronomers with the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Hawaii recorded a bright cloud of debris:

This was the result of the 1,340-pound spacecraft plunging into Dimorphos at 14,000 mph. Most of the debris is probably asteroid dust, but some of DART may be in there, too. A similar video was recorded by the 1-meter Lesedi telescope in South Africa.

Mission scientists say DART hit the asteroid less than 17 meters off center. Think about that: 17 meters off at a distance of 11 million kilometers. NASA still has the right stuff.

Now that the dust has cleared, astronomers are monitoring Dimorphos’s orbit to find out whether or not it has changed in response to the strike. Even a slight shift would prove that human tech can alter an asteroid’s trajectory–a possible strategy for future Planetary Defense.

more images: from Gianluca Masi using the Klein Karoo Observatory in South Africa; from Ernesto Guido using a remotely controlled 0.61-meter telescope in Chile; from Eliot Herman using a remotely controlled telescope in Siding Spring Australia