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All posts for the month July, 2012

A Dwarf Planet with Moons

Pluto has been in the news a lot lately. The New Horizons spacecraft is headed out to swoop past this icy dwarf planet and show us what it really looks like.  That will happen in July 2015 — just three years from now.  In the meantime, the Hubble Space Telescope keeps checking out this distant world and finding new moons around it. The HST observations are an ongoing project to make sure that mission planners for New Horizons have a good idea of the known hazards (i.e. things that the spacecraft could hit) as it whizzes past Pluto in a few years.

The dwarf planet Pluto and its five moons. Will HST find more? Courtesy NASA/STScI.

Last week, the HST folks announced the discovery of a fifth moon orbiting Pluto. For now, it’s called P5, and in time, it will get an official name.

Pluto’s moons, with the exception of its largest moon Charon, are pretty small. This newly discovered one is no bigger than 15 miles across.  Now, it’s kind of intriguing that Pluto has so many of its own moons, and scientists are busily figuring out how it could have gained such a following through its history. The current thinking is that these little moons  are debris from a collision between Pluto and another object early in the history of the solar system, and subsequently were swept into Pluto’s orbit.

Collisions ARE an important part of solar system evolution. Earth’s own Moon was most likely formed in the aftermath of a collision between the infant Earth and a Mars-sized object.  And, we still see collisions today: comets collide with planets, asteroids collide, objects in Saturn’s rings collide, and so on. Collisions are a fact of life when you live in a planetary system and people in planetary science are still defining and understanding the role that smashups play in the larger evolution of worlds.

The New Horizons mission is a small spacecraft that proposed to NASA after the Pluto Kuiper Express mission got cancelled by the agency due to lack of funds. New Horizons has moved out beyond the orbit of Uranus, carrying a suite of scientific instruments, including a set of cameras, radio science detectors, plasma and high-energy particle detectors, and a dust counter. It has already sent back data and images  Jupiter and some of its moons, and an asteroid.

Once the mission gets to Pluto, it will fly quite close to this frozen world and take massive amounts of data about its surface and atmosphere.  After that, the spacecraft heads out to explore more of the Kuiper Belt and relay information about this unexplored frontier of the solar system. Stay tuned!

 

The Star-Stuff Continuum

I haven’t been online much lately because in mid-June I suffered an injury to my neck that required an immediate operation and the aftermath of healing has limited how long I can sit in front of a computer.  But, I’m healing well, and am resuming my blogging (or at least trying to up my frequency of blogging). There’s a lot to write about — Higgs bosons, dark galaxies, some other news coming up later this week — so I’ll have plenty to dive into.

One of the things that occurred right after that sudden surgery was a little discussion in the post-op room about the level of potassium (chemical symbol K) that was showing up in my blood tests. While I was there waking up and sipping some ice water soon after surgery, I listened to the medical folks talking about what the measurements meant. I let my mind wander a bit, thinking about potassium and how it got to be in our blood chemistry.

You’ve all heard the term “star-stuff” enough to know that the elements that make up our bodies (and the structures of all life on Earth) came from stars. To be more succinct, much of the “stuff” we have in our bodies is from the ashes of long-dead stars. The oxygen, iron, calcium, on down to traces of potassium, and many other chemical bits were created in stars that are now no longer on the scene.  The hydrogen, of course, was there from the beginning of the universe.

About 4.5 billion years ago in our neighborhood of the galaxy (give or take a few eons), there was a population of stars doing what stars have always done:  fusing elements together, starting with hydrogen, and moving through carbon, nitrogen, oxygen, and so forth.  The local Sun-like stars did this, and when they died, they blew what they created out to space.  Stars much more massive than the Sun went through similar processes — blowing mass out to space eons before the end actually came. When these stellar behemoths died in supernova explosions, it set the stage for the creation of heavier elements. The propulsive force of the explosion scattered their “stuff” out  to interstellar space. All the materials from all the different star death processes ended up in the nebula that formed the Sun, planets, and on Earth, where we evolved using all those elements (and the chemical compounds they make up) as seed material for life.

Now, it’s a long trip from the bits of potassium made inside a long-dead star to the amount of potassium that exists in your body in blood particles.  But, suffice to say, without that dead star, I wouldn’t have been laying in the post-op unit, listening to medical personnel have a little conference about my blood potassium levels (and, it turns out it was no big deal — the issue resolved itself).  That day in the OR recovery room, I was thinking about things that I knew and have known for years about star stuff and elements. But, a little blood test made it much more personal to me and that potassium reminded me once again in a very personal way that I am, indeed, star stuff.