Exploring The Solar System: Mercury

Mercury

Does this place look familiar? “Ah,” you say, “It looks like the Moon. The first astronauts set foot there in 1969.”

Yep, it does resemble the Moon, somewhat. But, this is Mercury — named after the Roman god of travel and business. LIke its namesake, it does get around — but is limited to orbiting around the Sun once every 88 days. At its closest, Mercury is only 46 million kilometers from the Sun (that’s 28.5 million miles for those of you who are resisting assimilation into the metric collective). Compare that to the Earth (and Moon) — we orbit the Sun at an average distance of 149 million kilometers (93 million miles). As you might imagine, being so close to the Sun, Mercury can get pretty darned hot. In full sunlight, temperatures there top out at 426 Celsius (800F). At the poles (where the Sun doesn’t ever shine on Mercury) the temps are -203C (-333F).

I recently read a book called “Higher Than Everest” (available from Cambridge University Press and Amazon). In it, the author describes an “extreme expedition” to Mercury to do some cliff hiking — and he makes it sound like an entirely do-able kind of field trip.

Could humans make this kind of journey? Sure, given the right equipment and time to do it right. Before you ever left Earth, however, you’d need to get plenty prepared. Along with physical conditioning, you’d study maps of the planet, getting to know the cratered surface from old Mariner 10 images. Then, you’d need to get there, using a heavily-shielded spacecraft. After that, you’d need something to get you to the surface safely, and of course a protective suit to keep you cool and safe from the radiation environment once you stepped outside. The good news is that since Mercury’s gravitational pull is much less than Earth’s, you’d weigh a lot less than you would on Earth, even with the survival suit. The hike itself would be about like walking across rough terrain on Earth — lots of rocks and boulder fields. Climbing would be a bit more difficult just due to your bulky space suit. And, you’d need to be a lot more careful than you ever would on an Earth hike. But it could be quite the adventure!

Wanna look for Mercury this year? Your best bets in 2002 are to look to the western horizon immediately after sunset (never look directly at the Sun!) around May 4 and September 1st. If you’re an early riser, look along the eastern horizon immediately before sunrise during around June 21st and October 13th this year. It won’t be an easy sight to see, but it’s worth trying. Just remember to be careful and protect your eyes!

Exploring The Solar System

The Solar System

This is the solar system in which you live — minus the Sun, Pluto, and a boatload of ring particles, asteroids, moons, and comets. All these planets have been visited by spacecraft missions sent from Earth sometime in the last 40 years. Why do we routinely fling probes out to these worlds when it would be far more fun to simply visit them? Well, for starters, visiting other planets — even our own Moon — isn’t a simple proposition. I wish it were — science fiction stories make it seem easy, but they don’t always dwell in the millions of details that would accompany each crew into space. Sending people to space is a tough thing to do but eventually we’ll be out there walking the dusty plains of Mars and scooting above the rings of Saturn.

Humans have the invaluable eye of experience and judgment, which all explorers use to analyze their surroundings and figure out how things got to be the way they are. It’s one thing to look at a canyon in photographs taken by an orbiting spacecraft, but quite another to drive into that canyon, hike its walls, and analyze soil samples for some understanding of its chemical and geological evolution. We can send machines to do the grunt work, but they can’t do the analysis that a well-trained scientist can do in a single glance.

But, people need special environmental suits and spacecraft to protect them from the hostile environment of interplanetary space and the conditions at other planets. There’s no way right now, for example, that we can send anybody to the surface of Venus. We simply don’t have the technology put together to shelter people from the high temperatures and pressures that exist at the Venerian surface. Actually, right now we don’t even have an interplanetary spacecraft that can get them to the other planets. It’s far easier to send packages of specially-hardened electronics that can stand up to the punishing rigors of planetary exploration. It’s one thing to fry a spacecraft in the high radiation environment at Jupiter, for example, but obviously a far different proposition risk turning human explorers into crispy critters.

For now, however, we have to work with images and data sent back from our flotilla of planetary missions. We still learn a lot, and in a way, we’ll be better prepared for the time when our children and grandchildren are out there with pickaxes and soil sample kits doing the kinds of hands-on geology field trips that we can only dream of today.

Venus Born and Reborn

I read in the paper the other day about a newborn baby girl in Afghanistan and how her mother’s hopes for her future were looking a bit brighter now than in past years. I kinda wonder about her too — what will she grow up to be? Maybe she’ll become an astronomer and learn more about the world that is her namesake, or study to be a doctor, or raise a family in freedom, or be a political leader in her country.

This little Afghani Venus is named after the second planet from the Sun, an avatar revered in mythology as the goddess of love. What a lovely name for a tiny new life!

Yet, the planet itself makes the drought-ravaged lands of Afghanistan where baby Venus now lives look like a veritable garden of Eden. This distant world is veiled in noxious clouds, which hide a hot, poisonous, volcanic landscape where no human being could possibly live — let alone fall in love!

Venus in the glow of sunset, imaged by the astronauts onboard the shuttle Atlantis

Starting in early March, the planet Venus will make its own 2002 debut, in the evening skies just after sunset. If you have a clear view of the sky check it out after sundown — it should be a bright, beautiful, almost-but-not-quite starlike object hanging there in the deepening western twilight. Watch it night after night throughout the spring and summer. On the night of May 7 it will appear in close conjunction with the planet Saturn, and with Mars on May 10. It dances around with Jupiter on the evening of June 3.

None of these conjunctions are particularly mysterious or have any cosmic significance. They happen because as planets move around the Sun in their orbits sometimes they appear in the same part of the sky as seen from Earth. They aren’t close to each other, really, nor are they exerting some magical influence because of where they happen to appear. If you see five people standing out in a field and you move so that two of them are in line with each other it doesn’t mean that they are somehow cosmically aligned. Same with the planets.

If you want more information on where to look for Venus or any other night-sky sight from your location, point your browser to the Sky & Telescope web site. There’s an interactive JAVA star chartmaker that allows you to input your location — and will compute a chart for your viewing site. Give it a whirl!