Where in the Solar System is It?

What planet do we know of that has deserts and crater fields and looks rather reddish?  Where the sands of time have covered up any traces of water that may have flowed across the surface? That has scenes like this one?

Where is this?

One of the most intriguing things about studying the surfaces of other worlds is figuring out just how they came to be the way they are. Planetary scientists know of several processes that shape solid surfaces: cratering (made by incoming projectiles), weathering (caused by liquid or wind erosion (which is itself often termed “aeolian”)), volcanism (molten materials from deep beneath the surface that flow across terrains and cover over what was there before, or disrupt the landscapes with calderas and pits), and tectonism (the processes that fault and fold the surface of a planet or moon (such as earthquakes, mountain-building)).

So, if you look at a surface like the one shown above, you see no water, but you do see dunes and fields of sand and  dust. This tells you that at least wind-blown erosion and deposition are taking place.  You can also see some circular impressions that turn out to be the ancient, eroded remains of impact craters. Erosion takes time, which means that this surface is not  young and fresh. Weathering and deposition are covering up what’s left of these craters and various surface measurements give an estimated age of the craters themselves at about 140 million years old. And so we ask again: what planets in the solar system have evidence of aeolian (wind-blown) weathering and ancient impact cratering?  And, whose sands look some what reddish?

What does scene this tell you about the planet where this terrain lies? What assumptions can you make to help you guess where this scene is?  Think about it before dragging your pointer across the blank-looking area between the ( ) for the answer.

(It’s on Earth — in a desert area in Libya (northern Africa), that sports a pair of ancient impact sites called the Arkenu craters. This image was provided by astronauts aboard the International Space Station.)

More than Just a Surface Study

Due out on November 18, 2009

I got a nice surprise in the mail a week or so back — a beautiful  review copy of a magnificent book called Planetology: Unlocking the Secrets of the Solar System. It’s from the friendly folks at National Geographic and is written by planetary scientists Tom Jones and Ellen Stofan.  Somebody at NatGeo must have known what a fan I am of planetary science because this is the book I would have written if I were tasked to bring the beauty and excitement about planetary studies to a broad audience. (And, hey, just in case anybody from NatGeo sees this, I’m available to write books and documentaries!)

Planetology really is a nice collection of images coupled with very clear science writing. I’m in awe at the work that Jones and Stofan put in on it.

I paged through the book first, just drinking in the great images. Then, I went back and started reading. Now mind you, I took a few semesters of geology back in college and in graduate school I studied some planetary science. And, as most of my readers know, I’ve written about planetary science in my own books (Hubble Vision, and Visions of the Cosmos) and was co-editor of a well-known (and widely used) planetary science book, The New Solar System. So, I wasn’t coming to this book without some background.  In planetary science and geology classes we learned about the processes that shape worlds: volcanism, tectonism, impacts, and weathering.  Volcanism I’ll discuss below; tectonism is the faulting or folding (the deformation) of the top layers of a planet; impacts are just what they sound like — the craters gouged out when debris slams into a surface; and weathering is another term for erosion (which can happen when water runs across a surface, wind scours a surface, or in some severe cases, when acid rain erodes a surface).

I’m happy to see that this book takes a really inviting approach to presenting those processes and what they do to planetary surfaces. It does this by comparing and contrasting Earth’s scenes with how the same processes work elsewhere in the solar system. And sometimes, what we learn “out there” teaches us a valuable lesson about how it works right here at home on Earth. Planetary science is funny that way…

A lava flow on the Big Island of Hawai'i (Copyright 2007, Mark and Carolyn Collins Petersen)

Let’s take volcanism as an example. The book steps through how volcanism works on Earth, complete with some really cool pix of volcanos and the obligatory, but (to me) chilling images of what volcanism did to humans in Pompeii in 79 A.D.

Since I’m a volcano junkie, that section really spoke to me. But, the authors take the reader one step further and show how volcanism works on other worlds — the heart of comparative planetology.

This is where it gets really interesting, because volcanism doesn’t just heat up rocks on other worlds. It also heats up ice!  Which means that we get a great look at volcanism on Earth, Mars, Venus and Io, but we also get to see the cryovolcanoes of Europa and Triton and Enceladus and other frozen worlds of the outer solar system.

Ice volcanoes spew out material from Enceladus (as seen by the Cassini spacecraft).

For people who thought that volcanoes only spewed out lava, finding out that they can spew molten, sluggish ice or blast out ice geysers is quite a wake-up call!

Volcanism is just one part of the very intricate story told in this book about the processes that shape Earth and the other planets and moons of the solar system.

I’ve been through this book twice, and I’m about to head through it again. While it’s not a textbook (and it doesn’t need to be) it is a leisurely look at comparative planetology told in terms that we can all enjoy — no matter what our level of science education. Planetology is coming onto bookshelves starting November 18 (I have a link to it in my online store if you want to pre-order it) and I think it would make a great gift for somebody (or even yourself).

Check it out!  (And a tip of the hat to National Geographic for sharing a pre-release copy!)

And Climate Change

Sometimes you can’t keep ahead of the news. Especially in science.  As I was working on the climate change exhibits for California Academy of Sciences earlier this year, I’d keep tabs on research and discoveries in Earth sciences, particularly Earth’s atmosphere and oceans. And, as fast as I’d write up something from peer-reviewed science, there’d be more information and discoveries coming in.  Which is great, but when it comes to climate change, it seems like it might be chronicling drastic change that we neither need nor want.  But, that’s the nature of science research — it reports on what’s happening and tries to find out why it’s happening.If we’re smart, we heed what we see and take action.

Tomorrow there’s a peer-reviewed science paper coming out that I wish had come out earlier, since it would make a striking addition to the exhibits. It states that as Earth’s oceans absorb more carbon dioxide generated by human consumption of fossil fuels and other activities (which warms up oceans and causes them to become more acidic), sounds will travel farther underwater. What’s the big deal, you might ask.  Well, noisier oceans affect marine mammal, for one thing. And, there are likely other effects that reverberate throughout the ocean environment.

Image credit: © 2008 MBARI (Base image courtesy of David Fierstein). This illustration shows how increasing carbon dioxide in the atmosphere leads to an increase in the acidity of seawater, which in turn allows sounds (such as whale calls) to travel farther underwater.

This projected impact on ocean sound is the result of calculations by Keith Hester and his colleagues at the Monterey Bay Aquarium Research Institute (MBARI) in Moss Landing, Calif. Their paper is coming out in tomorrow’s (October 1, 2008) issue of  Geophysical Research Letters, a journal of the American Geophysical Union (AGU).

As the oceans become more acidic, sounds will travel farther underwater and the level of underwater noise will rise. This change in chemistry will have the greatest effect on sounds below about 3,000 cycles per second (two and one half octaves above “middle C” on a piano).

This range of sound includes many of the underwater noises generated by industrial and military activity, as well as by boats and ships. Such human-generated underwater noise has increased dramatically over the last 50 years, as human activities in the ocean have increased. For marine mammals that also use this range of sounds to communicate, it’s like having your neighborhood go from one of relative quiet to one where the neighbors are blasting their stereos and revving their engines all the time.

It’s a Place of Science Learning, John, Not Uninformed Posturing

So, last week there was a kerfuffle, as they like to say, over a U.S. presidential candidate’s using planetarium funding as a weapon against his opponent. It was silly and, in my opinion, made the guy who complained about the funding look pretty foolish and ignorant (and, as Phil Plait suspected, anti-science). I suppose you could conclude that the candidate hates science education, but I suspect in reality, he had no clue of what he was talking about and just grabbed the first thing he could think of to throw back in his opponent’s face. It backfired, as it should have. Sensible teachers routinely flunk students who wing it like that, particularly in science where there’s little tolerance for making up facts to suit an argument. There’s no reason we should put up with a candidate for president of the U.S. who doesn’t do his homework.

I don’t want to get into the various specifics of the argument, mostly because we already hashed it out over at Phil’s Bad Astronomy Blog. I’d rather talk about what good planetariums are.

I’ve been involved in planetarium show production for a long time, both as a lecturer and as a content creator. To me, a planetarium is a great gateway into the world of science. Astronomy itself is a great entry into other sciences. Point yourself in any direction in the sky and the list of sciences you can use to explain what you see is a long one:  physics, astrophysics, chemistry, biology, atmospheric science, planetary science, geology… just to name a few. And, the beauty of a planetarium is that you can teach all that stuff on the dome, simply by looking at stars, planets, and galaxies.

Sure, you might not end up in astronomy as a career, but a number of scientists cite their first visit to a planetarium as something that got them started in science. In fact, it goes beyond scientists — I recently read about an environmental lawyer who fertilized his interest in science by lecturing at his local planetarium. I guarantee you that a good planetarium production will ignite your interest in astronomy, an interest you can take with you wherever you go.

I remember MY first visit to one when I was in 7th grade. I couldn’t believe such a cool place existed. It took a few years before I got back to one, and even a bit longer before I got into creating shows for such places. I spent some time just before graduate school lecturing in one, sometimes several times a day. It never failed to amaze me how cool the visitors thought the experience was. Oh sure, there were always a few slouches who came in and tried to be disruptive. But, for the most part, the visitors were thrilled to be there and learn something about astronomy.

In the U.S., we need more and better science education — it leads to critical thinking and better-informed citizens, methinks (which, come to think of it, might scare a certain subset of politicians (and others) who thrive on having ignorant voters…)

If a planetarium can help spur kids into studying science and having fun with it, it ADDS to taxpayer literacy in our country, and money spent on education (if done wisely) can come back to us in the form of better educated teachers, more scientists, and involved, engaged citizens. So, I kind of have to wonder: what’s so bad about that?  And, why is attacking a planetarium’s funding (which was a very small amount of money compared to the money that the attacker has wasted or misspent through his actions over the decades as a senator, and certainly is well below the amount he has sunk into all his seven or eight homes) somehow a sign of political virtue?  Especially since there are bigger budgetary oxen to be gored. I just don’t see how huffing and puffing about a planetarium is anything but a nonstarter, unless the candidate is a supporter of decreasing science literacy for all of us.

Welcome to Haumea!

Haumea and its moons Hi'iaka and Namaka. Artist's concept by A. Feild, STScI

Let’s all give a big welcome to a newly named (but not newly discovered) dwarf planet orbiting the Sun out between 35 and 50 AU from the Sun. The new name is Haumea, given this week by the International Astronomical Union to honor the Hawaiian goddess of childbirth and fertility. In Hawaiian mythology, this goddess also represents the element of stone, which is very applicable to this dwarf planet. Observations of Haumea hint that this world is almost entirely composed of rock with a crust of pure ice — somewhat unusual for this region of the solar system.

Haumea is joined in its orbit by two satellites that are thought to have been created by impacts with other objects in the distant past, collisions that blasted parts of the surface away from Haumea. The debris likely re-coalesced to form the two moons. The first and largest moon is now named Hi’iaka, after the Hawaiian goddess who is said to have been born from the mouth of Haumea and the patron goddess of the island of Hawai’i. The second moon of Haumea is named Namaka, a water spirit who is said to have been born from Haumea’s body.