Category Archives: NASA

atmosphere, atmospheric science, climate change, Earth science, NASA, terra satellite

The Ash from a Distant Mountain

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Watching the Fires from Space

The Southern California Fires as seen by NASA's Earth Observing System Terra satellite. Courtesy NASA. Click to embiggen.

Up here in the Rockies we’re seeing the effects of the Station Fire near Pasadena in a most dramatic way — ash in the air, blood-red sunsets and a red Moon. There’s so much ash floating around that our mountains in the distance look like one of those Japanese watercolor paintings with mist-shrouded hills.

But, far from being mist, this stuff is the particulate matter distributed from the fires consuming more than 100,000 acres (and growing) of brush, trees, and homes.  Overnight the historic (and very busy) Mt. Wilson Observatory was threatened by the fire, but thanks to the efforts of fire crews, the observatory is (so far) spared from the flames. (Note: the link goes to Mt. Wilson’s webcam which may or may not be operating.  For more info about Mt. Wilson itself, go here.)

I find it fascinating to look at the satellite images of this fire — or any fire in any region on our planet.  As time goes by, you’ll see more of these images, with the smoke plumes heading out and affecting other areas.  What happens in one place on our planet inevitably affects other places.  This is why NASA and other space agencies are launching mission after mission to study our home world — to understand the processes it experiences and how all the various systems of our planet are linked together.  Often, as with the fires in SoCal, understanding and studying these topics is a matter of life and death.

asteroid, comet, impact site, impacts, NASA, near-earth asteroids, NEOs

Watch Out!

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Things that Go Bump in the Solar System

Jupiter got whacked last week, as most of you probably know. One question that I saw reiterated across many blogs and boards (mostly by people who have no idea how astronomy observations work) was along the lines of “Why didn’t the astronomers with all those big telescopes see this coming?”

As in so many areas of life, I have to respond that “it’s not the size that matters, it’s what you do with it.”  A big telescope all by itself doesn’t help you routinely find stuff getting ready to blast into Jupiter (or other planets).  In fact, a small one by itself won’t do it either — no matter how big the impactor is.  Both have to be pointed properly at the right place and right time, and they have to be able to “see” the objects.  If the object is too small — as the impactor at Jupiter was — you won’t have a chance of seeing it (from Earth, anyway) no matter how big your telescope is.  Each telescope and its instruments have limits to their resolution (essentially the size of objects they can detect — if something’s too small to detect, a given system just won’t be able to “see” it). Also, there’s the whole issue of scheduling — the big telescopes and the smaller ones operated by dedicated amateurs usually are taken up well in advance with planned observations. That’s not to say that they can’t be pointed at something once we find out about it — that’s called a “target of opportunity” and most facilities have allowances for such events in their schedules.  The catch is — you can’t observe the object or even until you know about it — or, if it’s big enough for you to see — until it wanders across your field of view as you’re studying something else. That’s just common sense.

Many comets and asteroids and asteroid debris that make up the “impactor class” are found by people and instruments who routinely scan the sky looking for such things. But, there’s a limit to how much sky one can scan each night, and observers are limited to the skies they can see from their sites. If there’s a comet beyond the horizon — well, it doesn’t get discovered that night by the observers who can’t see it.  Eventually the larger objects are found and observed over enough time that astronomers can calculate their distances and orbits. These are things that are larger than a kilometer or so in radius.

What about the small stuff? Well, it’s really, really tough to see, even with (and despite having) a large aperture telescope.  Yes, there are projects like Spacewatch, which explores populations of small objects in the solar system 20 nights per month (roughly), but those are not likely to be able to just look right out there and easily spot things as small as the projectile that bruised Jupiter.

Incoming objects fascinate (and scare) people, even if the chance of an impact on Earth is quite small most of the time. Yet, the big questions always come up: what if something’s headed for Earth? How will we find out about it?  How close will it get? Will we find out too late? What do we do?  Spacewatch and others do keep watch on Earth-approaching objects — if they are large enough to spot. Once something is discovered and charted, its orbit is plotted — which is not a one-time thing — orbits continually change as objects are perturbed by the gravitational influences of the planets they pass near. Also, it takes many observations over a period of time to accurately calculate an orbit — which then gives us a good handle on how close (or even if) it will come to Earth or another world.

With Spacewatch and other observation programs, we do have an early warning system of sorts.  And, if you’re interested in knowing what IS being tracked, there’s a new Web site to help you do that. NASA has just opened Asteroid Watch up for business. It’s a centralized Web resource for information on near-Earth objects. The site also contains links for anyone interested in such objects to sign up for NASA’s new asteroid widget and a Twitter account.  So, go check it out — and learn more about comets and asteroids that are being tracked and studied.