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.)

Death from the Skies

A Must-read!

So, imagine reading a book where humans are sitting on their lovely, water-rich planet, pretty much evolving along minding our own business, when we get wiped out by some “mysterious” thing from outer space. We’re humans at the mercy of a cold, uncaring universe. Classic science fiction, right?

Never gonna happen, right?

Sure.  Except when it does.

And how might that happen?  Good question.  It could be something that is very likely to occur someday: an incoming asteroid that doesn’t quite miss the planet but instead plows into the ocean, causing tsunamis and pretty much steam-cleans the planet before plunging it into an ice age.

Or, it could be as weird as a group of metal-poor aliens noticing that our planet is a great place to set up a mining operation, as long as they can get those pesky humans out of the way.

Or, it might be a supernova explosion — if one occurred close enough to us to make a difference.  Or, maybe our own Sun goes on the blink (as it’s scheduled to do in a few billion years) and wiping out life on our planet.

A book like that could be a blueprint for all kinds of woo-woo theories and arm-waving hysteria. Or, it could be a great way to learn about how these things might actually happen and what our actual chances are of experiencing them.

Phil Plait’s latest opus, called Death from the Skies!: These Are the Ways the World Will End . . ., is a great example of the second kind of book — an entertainingly written educational jaunt through the cosmic possibilities of destruction.

I have to say, he really does have a way with words! Even if those words are about all the possible ways that the universe can deal us a losing hand in the giant and ongoing game of cosmic poker. And of course, such events make for fascinating speculation. If you have even one scintilla of interest in how the universe really works, then you should read this book. It simultaneously educates, debunks, and entertains!

DFtS is about all the stuff that happens in the universe that might pose a threat to us here on Earth–things that do more than go bump in the night; things that have life-threatening consequences; things that we Earthlings might have to contend with or even survive should the universe decide to toss a few wild cards our way.

What kinds of things?  Oh, like those supernovae exploding and radiating us to death, or galaxy collisions having an effect on us; asteroid impacts and how they could occur;  what black holes could do to us;  attacks from metal-hungry aliens; and the granddaddy of all concerns: what’s going to happen to Earth when the Sun starts doing its dance of death; and… well, you’ll just have to read the book to find out about all of the things that Phil takes on and clarifies before our very eyes.

Now, not all of these events will necessarily happen or are happening to us right now.  And that’s an incredibly important part of what Phil writes about: what the chances really are that any of these events could occur.

Phil takes an approach that I’ve enjoyed in other books through the years — that of preceding each “catastrophic” event with a science fictional prose story about what such events might be like for the life forms (like people and dinosaurs, for example) that have to experience them. His book reminds me of one that one of my favorite astronomy professors wrote a long time ago (back in the 1970s, so you know that dates me). It was called Cosmic Catastrophes, by Gerrit L. Verschuur, a radio astronomer and author of a couple of other books called The Invisible Universe: The Story of Radio Astronomy and Impact!: The Threat of Comets and Asteroids. In his version of Cosmic Catastrophes (sadly, it’s out of print and not to be confused with Craig Wheeler’s Cosmic Catastrophes: Exploding Stars, Black Holes, and Mapping the Universe), Gerrit also tells a little story of catastrophe and agony before getting to some fairly serious science discussion about actual events described in each story.

In Death from the Skies Phil grabs the reader’s attention and bring scientific theories home in a much more personal way. After all, when an asteroid is aimed right at you (or a character in a very plausible-sounding story), you tend to take the science more seriously! He sketches his brief fiction scenes quite deftly and they lead very nicely into well-written and frequently-witty (in Phil’s inimitable style) discussions about the science behind the catastrophic events that could overtake our planet.

The book is definitely aimed at a broad audience, not just scientists or science “geeks”. He’s talking to the person on the street, the guy in line who asks you about comets when you mention you’re astronomer or the lady at the bank who, when she finds out you work on a spacecraft mission or you do sidewalk astronomy in your town, will talk to you about why she loves that picture of the Horsehead Nebula and asks you can you tell her what caused that dark cloud to look the way it does?

In other words, Phil’s talking to Every Person and explaining what scientists know about the cosmos and what might happen to us when the cosmic dealer hands us a bum set of cards. He doesn’t pull any punches and anybody who gets this book who is even the slightest bit interested in finding out what’s really happening in the cosmos will find it a great read. I know I did!

And, despite the attention-grabbing title, Phil leaves us with a pretty reassuring commentary:

Most of the Universe is lethal, but our little section of it is pretty cozy. The cosmos takes away, but it also provides. So go outside, enjoy a sunny day or a star-filled night. There is danger to avoid, but also beauty to behold, and you understand a little bit more about that sky now. And understanding is always good.

In Tonight’s Sky

If you live in the Americas take a few moments to step outside tonight after sunset and see if you can spot a crescent Moon next to a couple of bright, shiny objects in the west-southwest that you might mistake for stars, but are really the planets Venus and Jupiter. It should be quite a sight if you have a clear sky. (If you live elsewhere, you should be able to see the two planets, at least.)

The view to the WSW from my place (East Coast). Your view may vary. Made with TheSky, by Software Bisque.

I’ve been fiddling around with sky charts and views using a software program called TheSky (made by Software Bisque) and came up with what the program thinks my sky will look like from my location (on the East Coast of the U.S.).

Of course, the program assumes a crystal-clear sky, which is wonderfully heartening!  However,  it will be snowing, or at least cloudy, from my location. So, I might not get to see this lovely sight.

Update: the skies have cleared! So, we will likely get to see this sight tonight from where I live!

So, if you have clear skies, remember what they say in the cruise commercials: get OUT there!!

Oh, and if you live someplace chilly, dress warm. Take along a warm beverage, and a pair of binoculars to scan the sky for other interesting sights!  Make a night of it!

By the way, the program assigned colors to these two planets. They really won’t be blue and yellow… but look  more like bright, shiny starlike objects.  But, in order to differentiate them from the stars in the larger sky view that I took this image from, it’s easier to put a little color on the planets.  In other words, they’re just there to show you where to look near the Moon.  Just step outside and look to the west-southwest and you’ll get an eyefull!