Jupiter Caught an Extra Moon

"Gotcha! Jupiter Turned Comet into a Moon"
Space.com (September 14, 2009)

"Jupiter already has an abundance of moons, but from 1949 to 1961 it had another, temporary satellite in the form of a comet trapped in the gas giant's gravitational grip.

"Comet 147P/Kushida-Muramatsu was captured as a temporary moon of Jupiter in the mid-20th century and remained trapped in an irregular orbit for about twelve years, astronomers announced today...."

The astronomers weren't dawdling, and this isn't old news.

"...An international team led by Katsuhito Ohtsuka of the Tokyo Meteor Network modeled the trajectories of 18 'quasi-Hilda comets,' objects with the potential to go through a temporary satellite capture by Jupiter that results in them either leaving or joining the 'Hilda' group of objects in the asteroid belt. Most of the cases of temporary capture were flybys, where the comets did not complete a full orbit.

"But Kushida-Muramatsu was different: The team used recent observations tracking the comet over nine years to calculate hundreds of possible orbital paths for it over the previous century. In all scenarios, Kushida-Muramatsu completed two full revolutions of Jupiter, making it only the fifth captured orbiter to be identified...."

So What? (Remember the Dinosaurs?)

This is interesting theoretical science - but there's also a down-to-Earth application - which gets mentioned in the article in the words" "...'Fortunately for us Jupiter, as the most massive planet with the greatest gravity, sucks objects towards it more readily than other planets...'."

Whether or not an asteroid impact near the Yucatan peninsula was all it took to wipe out the dinosaurs or not, it didn't improve their odds any. So far, we've been lucky when it comes to rocks and hunks of ice falling out of the sky. The most serious recent hit we know of is the 'Tunguska Event,' back in 1908, was over a nearly uninhabited area.

If something like that went off over, say, Madrid or Perth: it would be a very bad day for people anywhere near the city; and economic problems from the destruction probably wouldn't stop at the national borders.

Not to be an alarmist, but I'm just as glad that astronomers are working to track the loose bits of debris in the Solar system. Now, if we can just get something like a space patrol set up - - - .

Related posts:

• "It Seems it Took More Than an Asteroid Hit to Finish the Dinosaurs"
  (April 29, 2009)
• "Asteroid Threat: Good News, We Have the Technology; Bad News - "
  (April 28, 2009)
• "That was Close! Near Earth Objects"
  (March 12, 2008)

Comets

Jupiter Imact: Hubble Took a Look

"Hubble Telescope Photographs Jupiter Impact Site"
Space.com (July 24, 2009)

"The unexpected impact of some space object with Jupiter, creating a dark bruise in the gas giant's atmosphere, proved a tempting enough target for scientists to put a hold on testing out the revamped Hubble Space Telescope and use its new camera to capture an image of the rare event.

"The plan, first reported by Spaceflight Now, was carried out yesterday so that astronomers could use the 19-year-old Hubble's unique capabilities to get an image of the spot, probably caused by a comet, before too many days had passed since the impact and Jupiter's atmosphere distorted the shape.

"The new Hubble image, released today, [Friday] shows a lumpiness to the debris plume caused by turbulence in Jupiter's atmosphere. The image is a natural color image of Jupiter in visible light...."

The dark patch is roughly the size of the Pacific Ocean, it seems. Which is pretty close to the headline I mentioned in an earlier post, saying that the hole in Jupiter's clouds was the size of Earth. Seen from space, the Pacific Ocean covers most of one side of this planet.

Why use Hubble? It gives the best, sharpest, look at Jupiter in visible wavelengths of any available telescope. "...Hubble managers decided that the impact event was rare enough and important enough to pause testing to get a look...."

This article gives a pretty good overview of what Hubble's observed, and what we know about the event on Jupiter. For one thing, the energy released in the impact was thousands of times more than what we experienced in the Tunguska event, back in 1908.

I've written before, about the prudence of setting up defenses before something leaves an ocean-size splat-mark on Earth.

Meanwhile, there's a lot to learn from that impact on Jupiter.

Related posts:

• "Big Impact on Jupiter: Astronomers' Field Day"
  (July 21, 2009)
• "Life Could Have Survived Earth's Late Heavy Bombardment"
  (May 24, 2009)
• "It Seems it Took More Than an Asteroid Hit to Finish the Dinosaurs"
  (April 29, 2009)
• "Asteroid Threat: Good News, We Have the Technology; Bad News -"
  (April 28, 2009)
• "Earth Day 2009: Don't Stop Breathing to Save Earth"
  (April 22, 2009)
• "Ten Not-So-Trivial Facts About Earth"
  (February 16, 2009)
• "How to Destroy Earth (It Ain't Gonna be Easy)"
  (July 9, 2008)
• "No Magnetic Field (to Speak of) For Mars: Asteroid Implicated"
  (May 12, 2009)

Big Impact on Jupiter: Astronomers' Field Day

"Jupiter Apparently Smacked by Rogue Object, New Images Reveal "
Space.com (July 20, 2009)

"Jupiter has apparently been smacked again by a rogue object hurtling through space, new images from amateur astronomers and NASA reveal.

"A giant scar-like blemish has appeared in the clouds near Jupiter's south polar region, which NASA observed in infrared after receiving a tip from an amateur skywatcher in Australia. The likely impact appears to have occurred exactly 15 years after the remnants of Comet Shoemaker-Levy 9 bombarded the planet in 1994 in an event that was widely predicted and scrutinized as it happened.

"The latest impact was not predicted, and it was caught by chance...."

The impact was discovered by an Australian amateur astronomer, Anthony Wesley, 44, who makes a living as a computer programmer. Situations like this, where an amateur astronomer is the first to notice a new phenomenon, aren't all that rare. Professional astronomers are paid to use their very expensive installations to watch places that are known to have valuable data. It's the amateurs who are everywhere else, ready to notice when something unexpected shows up.

Anthony Wesley almost missed this impact.

"...In an observation report posted to his Web site, Wesley said he almost missed spotting Jupiter's new blemish entirely because he was tired after a late-night skywatching session.

" 'It was a very near thing,' he wrote, adding that by 1 a.m. Local Time, he decided at the last minute to keep observing for another half hour.

" 'I'd noticed a dark spot rotating into view in Jupiter's south polar region and was starting to get curious,' Wesley went on. 'When first seen close to the limb (and in poor conditions) it was only a vaguely dark spot, I thought likely to be just a normal dark polar storm. However as it rotated further into view, and the conditions also improved, I suddenly realized that it wasn't just dark, it was black in all channels, meaning it was truly a black spot.'..." (Space.com)

The Space.com article is one of the first to take note of the July 19, 2009, impact on Jupiter. I've put links to several of the more recent articles toward the end of this post. The Space.com article is more detailed than many - although Today's CNN article does a pretty good job of passing details along.

A Bunch of Astronomers Looking at Jupiter: So What?

It's been 15 years since Comet Shoemaker-Levy 9 hit Jupiter. That was a scientific bonanza: since the comet had been tracked before impact, and the time and place of the impact was predicted, astronomers had a chance to set up an impressive array of sensors to record the event.

And, since it happened on Jupiter, the effect on Earth was somewhere between negligible and non-existent - as far as we know.

This impact was on Jupiter, again, but it wasn't predicted. Mr. Wesley didn't know he'd be giving the heads-up to professional astronomers a couple days ago.

Big Impact of Jupiter: Fascinating, but Not Earth-Shattering

Having the second big impact in 15 years happen on Jupiter isn't such a surprise. Jupiter is the biggest planet, in terms of diameter - and is vastly heavier than anything else in the Solar System except for the sun. Decades ago, someone referred to the planetary system we're in as being 'the sun, Jupiter, and debris.'

So, between being a big target and having a whacking great gravitational field to pull assorted rocks and ice balls in, being fairly close to the asteroid belt, and having an orbit that comets sometimes cross on their way to the sun, Jupiter is going to have big, heavy things falling on it fairly often.

What's a little disturbing about this latest impact is it wasn't predicted. Nobody noticed something approaching Jupiter before an Earth-size hole was blasted in the upper cloud decks.

Asteroid Impact Here? Still Not Earth-Shattering - But We Wouldn't Like it

I don't know enough physics to say what sort of energy is needed to punch a hole thousands of miles wide in Jupiter's upper cloud layers: but my guess is that I wouldn't want to be anywhere nearby when energy on that scale is released.

And, since Earth is only about 8,000 miles across, if something like what hit Jupiter last Sunday came down in, say, Antarctica, anywhere on Earth would be "nearby."

An event like that would push news about floods in Mongolia off the front page. It would probably even eclipse coverage of Michael Jackson's death. And, humanity would have a great deal more to worry about than getting ready for the Olympic Games next year.

I'd rather not find out whether or not there would be people around, ten thousand years after such an impact. Cockroaches, though, almost certainly would be. They've been through quote a few hard times on Earth.

We Have the Technology to Protect Ourselves

I was mildly surprised to discover that The Spaceguard Foundation was organized in 1996. I'd expected to find an earlier founding date. Serious discussions among and loose associations of astronomers concerned with tracking objects that might hit Earth go back decades.

We've got the technology to detect (most) largish objects that might hit Earth, track their orbits, and make pretty-good estimates of when and where they might hit. As they got closer, we'd be able to make increasingly accurate predictions.

We've also got the technology to do something about a big rock, or gravel pile, or slushball, headed our way. The relative merits of moving the incoming object so that it misses Earth, or breaking it up so that it hits, but in small pieces over a large area, have been discussed.

The 'breaking it up' scenario isn't, necessarily, as crazy as it may sound. Earth gets hit by around 2,000 tons of meteor every day. (Journal of the Royal Astronomical Society of Canada, via Harvard) Except for a few astronomers, we don't notice all those tons of stuff falling on our heads, because most of it burns up in the upper atmosphere.

My guess is that adding more tonnage would make a measurable difference, somehow. And, that it would result in a spectacular one-time-only meteor shower. And, in America, several thousand lawsuits for everything from emotional suffering to a disappointing vacation.

Earth and Asteroids: We've Been Lucky, So Far

I'd like to think that outfits like The Spaceguard Foundation will distract national leaders from whatever it is that they usually do long enough to get an effective detection and interdiction force in place. Before something like the Tunguska Event happens over someplace like Singapore or Dallas.

Related posts:

• "Life Could Have Survived Earth's Late Heavy Bombardment"
  (May 24, 2009)
• "It Seems it Took More Than an Asteroid Hit to Finish the Dinosaurs"
  (April 29, 2009)
• "Asteroid Threat: Good News, We Have the Technology; Bad News -"
  (April 28, 2009)
• "Earth Day 2009: Don't Stop Breathing to Save Earth"
  (April 22, 2009)
• "Ten Not-So-Trivial Facts About Earth"
  (February 16, 2009)
• "How to Destroy Earth (It Ain't Gonna be Easy)"
  (July 9, 2008)
• "No Magnetic Field (to Speak of) For Mars: Asteroid Implicated"
  (May 12, 2009)

In the news:

• "Mystery impact leaves Earth-size mark on Jupiter"
  CNN (July 21, 2009)
• "Jupiter 'struck by large object' "
  BCC (July 21, 2009)
• "Jupiter Struck by Object, NASA Images Confirm"
  Reuters, Via FOXNews (July 21, 2009)

Background:

• The Spaceguard Foundation
  Nec cum fiducia inveniendi
  Nec sine spe
  • This is the mirror site hosted by Harvard. There are at least two others, in
    • Europe (Italy)
    • Japan
• "Meteor News (A Size Classification of Meteoritic Material Encountered by the Earth)"
  Millman, P. M., Journal of the Royal Astronomical Society of Canada, Vol. 46, p.79, via Harvard

Big Changes on a Big Planet: Red Spot on Jupiter Has Company

"Jupiter's Spots Change Dramatically"
Space.com (May 26, 2008)

"A potentially historic change is occurring on Jupiter. An upstart storm now rivals the gas giant's Big Red Spot as king of storms, astronomers announced last week.

"The Little Red Spot, as it was named upon discovery in 2006, shows both size and speed in threatening to knock the former champion off its perch, with Junior's maximum winds reaching 384 mph (172 meters per second)...."

"A third red spot on Jupiter was also announced last week by a different team, joining its larger super-storm cousins. The Great Red Spot has raged on for at least two centuries and perhaps as much as 350 years, ancient observations suggest...."

"Such changes in Jupiter's weather come as part of a global upheaval that began before the New Horizons spacecraft visited last year. The idea that Jupiter is undergoing global climate change was proposed in 2004 by Phil Marcus, a mechanical engineer at the University of California, Berkeley. He predicted large changes in the southern hemisphere starting around 2006 that would destabilize jet streams and spawn new storms."

Exciting times for astronomy: particularly since there are now space-based observing platforms that have clear views of the sky.