Space Weather

[Jherrith]

A VOLCANIC COMET BLOWS ITS TOP: So you think you know what a comet is? Think again. Comet 29P/Schwassmann-Wachmann is challenging old ideas. Astronomers call it a comet, but, really, "giant space volcano" might be a better description. It's a 60-km-wide ball of ice orbiting the Sun beyond Jupiter, and it appears to be one of the most volcanically active bodies in the entire Solar System.

Comet 29P just blew its top ... again. In late September 2021, 29P erupted four times in quick succession, blowing shells of "cryomagma" into space. Arizona amateur astronomer Eliot Herman has been monitoring the debris:



"Initially it looked like a bright compact object," says Herman. "Now the expanding cloud is 1.3 arcminutes wide (bigger than Jupiter) and sufficiently transparent for background stars to shine through."

When this object was discovered in 1927, astronomers thought they had found a fairly run-of-the-mill comet, unusual mainly because it was trapped in a nearly circular orbit between Jupiter and Saturn. 29P quickly proved them wrong as it began to erupt over and over again. Modern observations show that outbursts are happening as often as 20 times a year.

"The current outburst, which began on Sept. 25th, appears to be the most energetic of the past 40 years," says Dr. Richard Miles of the British Astronomical Association (BAA). "Within a span of only 56 hours, four eruptions took place in quick succession, creating a 'superoutburst.'"

Miles has developed a theory to explain what's happening. The "comet," he believes, is festooned with ice volcanoes. There is no lava. Instead, the volcanoes are powered by a mixture of liquid hydrocarbons (e.g., CH4, C2H4, C2H6 and C3H8) akin to those found in the lakes and streams of Saturn's moon Titan. In Miles's model, the cryomagma contains a sprinkling of dust and it is suffused with dissolved gases N2 and CO, all trapped beneath a surface which, in some places, has the consistency of wax. These bottled-up volatiles love to explode when a fissure is opened.


Above: A time series of previous outbursts from June 2020 - April 2021. These are all small compared to the current superoutburst. Source: Mission 29P.

In a seminal paper published 5 years ago, Miles studied more than a decade's worth of eruptions, and he found some patterns. The data suggest that 29P rotates every 57.7 days. The most active vents are concentrated on one side of the ice-ball in a range of longitudes less than 150 degrees wide. At least 6 discrete sources have been identified.

While most outbursts fade within a week or so, this superoutburst is still visible. The rat-a-tat-tat eruption in September boosted the comet's brightness 250-fold, and it hasn't declined much since then. With an integrated magnitude between +10 and +11, the expanding cloud is well within reach of backyard telescopes.

"Comet 29P can be seen with an 8 inch 'scope," says Herman. "In smaller instruments it will appear to be a bright dot. To resolve the cloud and photograph individual stars shining through it, I used the big half-meter iTelescope T11."

Ready see something weird? 29P is located in the constellation Auriga, easy to find high in the sky at midnight.

[thelufias]

When I read this I was thinking how small and puny Earth really is compared to Jupiter....

[Jherrith]

SOMETHING JUST HIT JUPITER: Last night, German astronomer Harald Paleske was watching the shadow of Io create a solar eclipse in the atmosphere of Jupiter when something unexpected happened. "A bright flash of light surprised me," he says. "It could only be an impact." Follow the arrows to the fireball:



Reviewing his video frames, Paleske quickly ruled out objects such as airplanes and satellites, which might be crossing Jupiter at the time of his observation. The fireball was fixed in Jupiter's atmosphere. It first appeared at 22:39:27 UT on Sept. 13th and remained visible for a full two seconds. The most likely explanation is a small asteroid or comet striking the giant planet; an asteroid in the 100m size range would do the trick.

This isn't the first time astronomers have seen things hitting Jupiter. The most famous example is Comet Shoemaker-Levy 9 (SL9), which struck Jupiter in July 1994. At the time, most astronomers thought such collisions were rare, happening every hundred years or so. Since SL9, however, amateur astronomers using improved low-light cameras have observed more than a dozen impact flashes in Jupiter's cloudtops. The Solar System is more dangerous than we thought.

Paleske pinpoints the fireball at Jovian latitude 106.9° (CM1), longitude +3.8°. Other observers are encouraged to monitor the location for debris. Previous impacts have sometimes created inky clouds -- probably the remains of the impactor itself mixed with aerosols formed by shock-chemistry during the explosion.

[thelufias]

Wow...that was pretty big....

[Aelin]

Wasn't exactly easy to find, but here a video with a meteor saw in a part of France
https://www.leparisien.fr/sciences/le-meteore-observe-dimanche-dans-le-ciel-de-bretagne-viendrait-dau-dela-de-neptune-06-09-2021-242OBUN3KZHLHCNEKYTKJDB3GQ.php

When they talked about it on a radio the next morning, they said it was at 3:50AM. Wrong hour but I'm not surprised.

[Jherrith]

RARE NAKED-EYE NOVA: Every 20 years or so, a thermonuclear explosion occurs on the surface of RS Oph, a white dwarf in the constellation Ophiuchus. Yesterday it happened again. On Aug. 8th, the brightness of the tiny star increased 600-fold, from magnitude +12 to +5. Keith Geary of Ireland was the first to notice. Hours later, Italian astronomer Ernesto Guido and colleagues photographed the outburst using a remote-controlled telescope in Australia:



This is called a "recurrent nova," and it is rare. In the whole Milky Way galaxy, only 7 star systems are known to produce such explosions.

RS Oph is actually a binary star--a very lopsided one. On one side is a white dwarf, on the other is a red giant. There's very little distance between the two, so the gravity of the white dwarf is able to pull gaseous material off the larger star down onto itself. Every couple of decades, enough matter accumulates to trigger an explosion. The last time this happened was back in 2006.

At 5th magnitude, the current outburst is visible to the unaided eye, albeit just barely. Binoculars or a telescope will allow you to see it with ease. Look south after sunset. Ophiuchus hangs high in the sky just above the better known constellations Scorpius and Sagittarius. Sky maps: simple, detailed, really detailed.

[thelufias]

Anything in space is amazing....even if I don't see any of it while it's happening due to weather LOLOL

[Jherrith]

THE PERSEID METEOR SHOWER IS UNDERWAY: Earth is entering a stream of debris from Comet 109P/Swift-Tuttle, source of the annual Perseid meteor shower. Although it won't peak until mid-next week, the shower is already active. Last night alone NASA cameras detected more than a dozen Perseid fireballs over the USA, and Petr Horálek photographed this beauty burning up over the Czech Republic:



"I captured our first Perseid of the year over Proseč on Aug. 3rd," reports Horálek. "Its rainbow hues were visible despite suburban light pollution."

109P/Swift-Tuttle is a huge comet with a broad debris stream. It takes Earth weeks to cross it. The shower will probably be most intense on Aug. 11-12 (Wednesday night through Thursday morning) when our planet is closest to the stream's dusty core. Adjacent nights could be almost equally good.

When should you look? Perseids may be seen any time after ~10 pm. Rates increase sharply after local midnight when the constellation Perseus is high in the sky (sky map). Observers in dark-sky sites can expect to count dozens of meteors during the moonless hours before sunrise.

Pro tip: Get away from city lights! Light pollution kills meteors, as shown this composite image of last year's Perseid shower:



Tomáš Slovinský and Petr Horálek took the pictures last August from widely spaced locations in eastern Europe. "The left photograph comes from the darkest area of Slovakia – Dark Sky Park Poloniny with a Bortle 2 sky," explains Horálek. "The right image is from Seč lake in the Czech Republic, where you can find a less-dark Bortle 4 sky. The difference between these two classes of sky is about a thousand naked-eye stars and innumerable faint meteors."

[thelufias]

Folks were freaked out when they saw this:

It's a Bird, it's a Plane....and it's NOT Superman  In The Sky

[Aelin]

Then I guess that metor can be one of the Alpha Capricornid meteors.
https://www.bbc.com/news/world-europe-57962384