Category Archives: impact site

hubble space telescope, impact site, Jupiter, planetary science

Debris-sweeper of the Solar System

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Jupiter

Jupiter as seen through HST's WF3. NASA, ESA, M.H. Wong (University of California, Berkeley), H.B. Hammel (Space Science Institute, Boulder, Colo.), A.A. Simon-Miller (Goddard Space Flight Center), and the Jupiter Impact Science Team.

By now, most people have heard that Jupiter got whacked earlier this month. The event was witnessed live by Anthony Wesley, an amateur astronomer living in Australia. Astronomers raced to observe the impact site to see if the debris plume could give them a clue to just what it was that hit the Jovian cloud tops. Among the telescopes trained on the site was Hubble Space Telescope and its Wide Field Camera 3. The results of that observation are in, and it seems that Jupiter was smacked by a giant meteor.  The image at left (on which you can click to massively enJovianate) shows where the meteor collided with the atmosphere on June 3 (the circle on the right-hand image). There’s no dark debris cloud as we’ve come to expect from other impact events.  This tells us that the meteor didn’t get very far into the clouds, since it didn’t explode and scatter dark debris around the region.

The flash of light recorded by Anthony Wesley during the event is created by the same type of activity that creates a “shooting star” in Earth’s atmosphere. The incoming object is moving at very high speeds and when it speeds into the atmosphere, a shock wave is generated by the resulting ram pressure. That shock wave heats the object to extremely high temperatures. That heats the atmospheric gases along the object’s path, and it also vaporizes a layer of the object’s surface. On Earth, what’s left of the object — if it makes it all the way through the atmosphere — falls to the ground as meteoritic material. On Jupiter, it just gets swallowed up by the clouds.

It used to be (back in the Shoemaker-Levy 9 days) that impacts into Jupiter were considered rare.  Not so much any more. We have 24/7 observations of the planets using vastly improved telescopes and sensors — and now, it turns out that Jupiter gets impacted by meteroids pretty frequently. Astronomers think this could be happening perhaps every few weeks or so.  We were lucky that someone was watching when this last one occurred, and I imagine that Jupiter-watchers will be keeping a close eye out for other impact events like this. Jupiter plays an important role in sweeping up debris in its path, and it very likely filtered out a lot of large debris early in solar system history — acting as a sort of protector for the inner planets. That means that Jupiter could have played a large role in shaping our solar system by lassooing many objects before they could whack into Mars, Earth, Venus, and Mercury.  If  so, and we didn’t have Jupiter, who knows what the inner solar system might look like now?  There’s no doubt that Jupiter has swept up much debris, but can it have other effects?

On the other hand, there is research supporting the idea that Jupiter’s presence might have increased the impact rate at Earth and the other planets over the history of the solar system (thanks to Daniel Fischer for reminding me of that research).  If that’s the case, you could still ask the same question:  if not for Jupiter, what would our solar system look like now — particularly the inner planets?  And, what role could Jupiter still be playing with the remaining solar system debris that still makes its way around the Sun in orbits that sometimes take it a little too close to Earth (and other worlds)  for comfort?  This is something that planetary scientists are seeking to understand as they map the orbits of solar system “stuff” and add what they find to their understanding of the complex mechanics of space debris and the worlds of the solar system.

amateur astronomy, astronomy, astronomy news, impact site, Jupiter

Something Smacked Jupiter… Again

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Is it Rare, or Not?

The June 3 impact of something on Jupiter, courtesy of Anthony Wesley of Broken Hill, Australia, and posted on spaceweather.com

The planet Jupiter got smacked again by an object this past week.  Recall that in 1994, pieces of Comet Shoemaker-Levy 9 blasted their way into the Jovian cloud tops.  At the time, people called it a once-in-a-lifetime event. That is, they did until something else plowed into Jupiter on July 19, 2009.

In an amazing coincidence, a major research paper came out this week, explaining just what it was that impacted Jupiter in 2009.  In another coincidence to THAT coincidence, the same observer who first chronicled the 2009 impact — Australian amateur observer Anthony Wesley — also saw the one that occurred a few days ago.  Christopher Go of the Phillippines captured a video of the event that sent a flash of light out from the Jovian cloud tops. Both are posted at Spaceweather.com, along with frequent updates.

You might be tempted to ask, doesn’t it seem like Jupiter’s getting hit a lot more lately?  The answer is: probably not.  In fact, Jupiter maybe getting less whacked NOW than it was in the past, back when the solar system had a LOT more debris flying around in orbit around the Sun and amongst the planets.  The difference is that we have people watching Jupiter all the time — well-equipped and qualified amateurs — and they’re bound to see these things happening, simply as a consequence of having more people pay attention. And, Jupiter being what it is — massive, strong gravity, and surrounded by debris in various orbits — it’s bound to get whacked pretty frequently.  We just haven’t always had the chance to see it happen.

Think of it this way: if trees fall in the forest on an average of once a day and nobody’s there to see it happening, we could come to the conclusion that trees falling in the forest are rare things. But that would be only because we aren’t looking. It’s an erroneous assumption, of course.  And, once we start putting people in the forest to watch the trees fall, we’d then find out that they’re falling once a day.  But, that doesn’t mean that more trees are falling. It just means we’re watching more. It’s probably the same with Jupiter. We’re watching it more and catching more of these events that could be very commonplace out in the Jovian neighborhood.

Jupiter has a long history of sucking up and sweeping in debris (comets, asteroids, etc.) throughout the life of the solar system.  In the beginning, it probably saved Earth’s skin more than once, by intercepting larger bodies that could have whacked the young Earth and changed it into something that might not be the planet we know and love today.  It’s still picking off debris today, and we’re fortunate enough to now have the technology to see it happen.

Now, about that paper explaining the 2009 collision.  When the impact occurred last year, scientists immediately turned their attention to the aftermath of the collision. They used a whole host of observatories on (and orbiting above) Earth. They mapped the thermal changes in the impact site (in other words, the temperature changes) and searched out spectral evidence of chemical elements that were part of the impactor (that is, they examined the planet in different wavelengths of light to tease out the fingerprints of chemical elements given off during the collision).  It now turns out that the evidence points toward an asteroid plowing into the cloudtops of Jupiter.  Critical examination of the impact debris suggests that the asteroid came from a family of bodies called the Hildas — a secondary asteroid belt that orbits near Jupiter and has about 1,100 members. Hildas are mainly rocky bodies that may also contain some ice.

This past February, when I was out at NASA Jet Propulsion Laboratory for a meeting, I had dinner with an old friend — Padma Yanamandra-Fisher — who was part of the team working on the data analysis of the impact debris. We talked about the event and I asked her if the impact could have been an asteroid. At that time, she was just finishing analysis, but she thought that it sure looked like an asteroid had been the culprit in the collision.

What about the impactor last week?  What’s it made of? It’s too soon to tell. Scientists are busily studying the impact site. There’s not much of an impact cloud to study, but they can take infrared measurements of the zone where the event occurred and get some idea of what the incoming debris could have been.  As with all ongoing science, stay tuned!