Category Archives: venus

'Casts, Jupiter, Mars, Mercury, saturn, venus

Awesomeness

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Celebrate It

I just read somewhere that March 10th is the International Day of Awesomeness.  It’s probably not an official government holiday or anything, but seems to exist to celebrate all things awesome.  So, what could be more awesome than the starry sky?  Living where I do (high in the mountains) with reasonably clear skies on many nights, I can step outside and look up and grok the awesomeness of the stars. And, this past week or so — and into March — the awe-inspiring sight of the planets Venus, Jupiter and Mercury just after sunset.  Mars is rising in the East, and if you wait a few more hours, you can see Saturn rising very late in the evening.  If you have binoculars or some kind of telescope, so much the better. You can check out Jupiter’s moons, for example. Or, if our own Moon is up, you can scan its cratered surface.  That’s the kind of astronomy awesomeness that gets people hooked on stargazing for life.

Speaking of telescopes, I know that people have a lot of preconceptions and misconceptions about ‘scopes.  When I worked at Sky & Telescope, we regularly answered questions in our magazines about the “best” scope to buy, the “most economical” and so on. Truth is, what you buy depends on what you want to look at, or if you’re planning to do astrophotography. Or, if you just want something you can easily pick up and take outside.  That’s where binoculars come in handy, and I’ve always recommended people start out with a pair of 10x50s as a good choice.  But, telescopes can give you awesome views, too.  I’d recommend you peruse Sky&Telescope.com or Astronomy.com for some good advice there.

The Galileoscope. Courtesy Galileoscope.org.

A former colleague from Sky & Telescope got involved a few years ago in a cool project called the Galileoscope. It was originally created to help celebrate the Interational Year of Astronomy in 2009. The Galileoscope is a small, build-it-yourself telescope that thousands and thousands of people have constructed and used to look at the sky. It’s a perfect way to introduce children to the sky and the instruments we use to observe it with.  You can learn more about the Galileoscope here, including where it can be purchased.  By the way, if any readers work in or run planetarium or science center gift shops, there are special discounts for bulk purchases to sell in gift shops. Check it out!  It’s awesome in its own right and worthy of celebration!

I mentioned above about how the planets are lining up for some gorgeous views in the next few weeks.  In fact, I focus on those views in the latest installment of Our Night Sky, the monthly stargazing program I produce for Astrocast.TV.  So, if you’re into some planetary viewing awesomeness, check it out. It’s about four  minutes long, and along with the planets, we look at a few constellations and a couple of deep-sky objects. It’s enough to get you started on some awe-inspiring sightseeing through the cosmos!

 

 

planetary history, planetary climates, planetary science, planets, venus, Venus Express

Planetary Habitability

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What Does it Mean?

In my last blog entry, I talked about oceans on ancient Mars and the evidence for them that planetary scientists are finding in craters on the Red Planet. All the questions about water on Mars really point to a big question about habitability — that is, a world’s capability of sustaining life.  There’s a sort of rote list of things that planetary scientists recite when it comes to assessing what a world has to support living beings. It has to have water, warmth, and organic material (food, essentially) for the life to exist. Those things are important for habitability.  So, if Mars had water in the distant past, and if it had warmth (from volcanism or heating from its core or if it had an atmosphere that could trap heat), then two of the three conditions for life would have been met. Food — organic material — would be a simple chemical problem to solve. Here on Earth, food for life ranges from the stuff you and I eat every day to the needs of such one-celled beings as bacteria that munch on sulfur.  Obviously, early Mars didn’t have gourmet delights that we could eat, but it could well have had plenty of delicacies for one-celled organisms.  So, the planet could have been habitable.  If we decided to live there in the future, it could still be termed habitable, but only just barely and we’d have to bring along habitats to take advantage of the barely habitable landscape. But, it could be done. And, it likely will be done.

So, we know Earth is habitable (still). And, Mars was and could be. But, what about Venus?  You know, that beautifully bright starlike object that’s making a nightly curtain call in our western skies after sunset?  Yeah, that one.  It’s gorgeous to look at, but if you landed on Venus, you’d fry in an instant, if you weren’t crushed to death first by the hellishly heavy and hot atmosphere.  So, how could this volcanic, sulfurous world be habitable?  Clearly it isn’t right now, but it may have been in the past.

What early Venus could have looked like. Could it have had a water ocean? Or was it more likely a molten world with a wet atmosphere? What happened to it? Credit: J. Whatmore.

Scientists at the European Space Agency are operators for the Venus Express orbiter, which has sent back data suggesting very strongly that early Venus could have water — perhaps even an ocean of it — and may have begun its planetary life as a much more Earthlike world. The spacecraft measured the escape of molecules of hydrogen and oxygen from Venus out to space.  The rate of escape of hydrogen is roughly twice that of oxygen, and this indicates that water is the source of these escaping materials. There’s also a tracer element called deuterium that also tells scientists that water has been escaping the planet. Deuterium is a heavy form of hydrogen, and it would have more difficulty escaping the planet’s gravitational pull. The presence of large amounts of it in the upper atmosphere of Venus tells us that water has also escaped and left the deuterium behind.

It’s probably unlikely that Venus had Earthlike oceans as shown in the artist’s concept above.  If it did have standing water, those pools and/or small oceans could have been formed when comets slammed into the molten surface.  If that happened, and if conditions were right, Venus could have been habitable for a short time in its early history. If that’s true, then it begs the question of whether life could have arisen on the planet, only to be snuffed out by Venus’s subsequent changing climate.  It’s an interesting idea and one that needs to be explored more.

However, the more likely scenario is that the newborn Venus had no oceans, but sported a very wet atmosphere overlying the molten surface.  Over time, sunlight broke the water molecules into hydrogen and oxygen (a process known as “photodissociation”). The newly freed gases fled to space, leaving behind the deuterium. The escape process cooled things down enough, and the surface cooled.

There’s still a lot of “ifs” in these scenarios, but the evidence for water (past and present) is strong, based on the Venus Express data.  It’s a good hint that the Venus we see today — hot, arid, miserable, and volcanic — wasn’t always this way.  And, it adds more to our store of knowledge about just when a planet can be habitable in its history — provided the conditions are right.

Stay tuned!