Category Archives: hubble space telescope

Debris-sweeper of the Solar System

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.

Billions and Billions of….

Stars in Billions and Billions of Galaxies

Take a good look at this picture.  Go ahead, embiggen it. Check it out. I’ll wait.

A view of 12 billion years of cosmic history -- courtesy the Hubble Space Telescope.

What you’re looking at are galaxies. There are 7,500 of them in this image, which covers a very small angular area of space. The most distant galaxies lie more than 13 billion light-years away. That means the light captured in this image of those galaxies was shining a few hundred million years AFTER the Big Bang — the event that resulted in the birth of the universe.  The closest galaxies in this image emitted their light about a billion years ago.

When you look at this image, you’re gazing at a slice of cosmic time, a snapshot of galaxies in nearly every stage of formation and evolution.  If you looked in every direction, across the entire sky, the view would be similar to this — galaxies as far as we can detect. Billions and billions of galaxies, each one comprised of anywhere from a few hundred million stars to hundreds of billions of stars.

Think about that as you gaze at this picture.

That’s a lot of stars.  And, you have to wonder if we really are the only ones out here in this vast cosmos to appreciate that fact.  Are we the only life capable of looking up and wondering if any of those other stars have planets and life? I often think about that concept — as I  wonder what the future of the cosmos will be; and think about the glories of past histories in other galaxies — glories we can only appreciate as a dim glow from a galaxy long, long ago and far, far away.