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Planet or Not…

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Pluto Has Moons

The Pluto system. Courtesy STScI/NASA/ESA

That distant world called Pluto has surprised astronomers again, yielding up yet another moon.  Pluto’s largest moon is Charon and was discovered in 1978.  Two more — Nix and Hydra — were found in 2005. The new one, called P4 (for now), is quite small, somewhere between 13 to 34 kilometers across, and small enough that it was probably missed in earlier images of the system taken by Hubble Space Telescope. This latest HST image was taken as part of  a search for ring material around the distant dwarf planet, in support of the New Horizons mission, which is en route to Pluto.

So, how would Pluto, itself a small world like many others in the outer solar system, get moons?  The current thinking is that a collision between Pluto and another world early in the history of the solar system would have flung material out into orbit. Eventually, the pieces and parts would have coalesced back together, forming the family of moons we see today.

When I read this story, the first things I wondered were “Why search for rings around Pluto?”  and “Where would the material for Plutonian ringlets come from?”  A long-ago collision would have provided material for rings, but by now, that material would have been cleared away or coalesced into moons, such as Nix, Hydra, P4 (and maybe even Charon?).  To maintain a ring system, you need a constant source of material being tossed out to space.  At Pluto, that source may well be material “chipped away” from the icy surface by the impacts of tiny micrometeoroids.  That would provide chips of ice to form a faint, thin ring. If it exists, it hasn’t yet been detected. But, HST would be the best instrument we have at this time to find the ring.  Once New Horizons gets there, it may well “see” the ring, if it exists.

I like it when HST finds things like this. It’s a continuing reminder that the venerable telescope has a lot of life in it yet; and will keep surprising astronomers with new finds.

astronomy news, hubble space telescope, NASA, planetary science

A Million Peeks at Space

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Hubble Makes a Milestone Science Observation

This is an artist's concept of the extrasolar planet HAT-P-7b. It is a "hot Jupiter" class planet orbiting a star that is much hotter than our Sun. Hubble Space Telescope's millionth science observation was trained on this planet to look for the presence of water vapor and to study the planet's atmospheric structure via spectroscopy. Planets with orbits inclined nearly edge-on to Earth can be observed passing in front of and behind their stars. This allows for the planetary atmospheres to be studied by Hubble's spectrometers. Hubble's unique capabilities allow astronomers to do follow-up observations of exoplanets to characterize the composition and structure of their atmospheres. Courtesy NASA/ESA/G. Bacon (STScI)

Telescopes and the many different instruments that can be attached to them are made to look at the sky and ferret out the hidden mysteries, open our eyes to dim, distant objects, and reveal a million things we didn’t know were out there. Your backyard telescope can do this — as can the mightiest scopes on — or off — our planet.

The Hubble Space Telescope made its millionth science observation on July 4th, using a special instrument called a spectroscope to study the light from a planet a thousand light-years away. The planet is called HAT-P-7b, and HST was looking for signatures of water vapor in the planet’s atmosphere.

It does this by looking at the atmosphere of the planet as it passes in front of its star. The light from the star shines through the gaseous envelope around the planet, and the spectral fingerprints of “stuff” (like water vapor) that is in that atmosphere will show up in the data taken by the spectrometer.

Hubble is quite well-equipped to search out such signatures, and its successor — the James Webb Space Telescope — will be even better able to do such observations. This is the kind of science that HST was built to do — and it’s the kind of science that really grabs my imagination.  It’s really quite cool to think that a telescope orbiting our planet can peer across a thousand light-years of space and spy out the merest whiff of chemical signatures in the atmosphere of another planet.  THAT is what makes this milestone so very, very cool!

You know what else I find very cool?  Back when HST was in severe trouble because of its mirror problems, there were people who felt that we’d wasted our money, that the telescope was a bungle. One of them was Senator Barbara Mikulski of Maryland, now chair of the Senate Commerce, Justice, Science and Related Agencies Appropriations Subcommittee.  She even went so far as to call Hubble a “techno-turkey” and I remember to this day seeing the anger on her face as she did it.  I even quoted her in my book about Hubble (Hubble Vision).

Yet, to her credit, she did step up and champion the cause of repairing the telescope. So, I think it’s cool that we have at least one politician who recognizes the value of science and, as she always points out, the value of inspiring children to become stargazers, scientists, astronauts, and engineering professionals.  I’m glad to see that she is celebrating the millionth observation too — we need many, many more to come.

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By the way, I want to thank the folks at TeachStreet for featuring this blog as one of the Featured Astronomy Blogs. I’ve rambled through their website and they have links to a number really fine writers.