25 February 2012

Look! Up in the sky! It's a planetary alignment!


If you've been paying attention to the western sky just after dusk in recent weeks, you've been treated to a really great show as the moon, Venus and Jupiter have been engaged in a nightly waltz with one another. Over the course of the next few weeks, Jupiter and Venus will continue to align so keep an eye out for it. If you have an unobstructed view of the western horizon next week, you'll get a glimpse of Mercury too.

This video from NASA explains what's going on in the not-uncommon alignment and what to expect in the weeks ahead.

Those objects are a nearly unfathomable distance from the Earth and it's really neat to just look up at them and ponder. A lot of people like to read all sorts of meaning into objects in the nighttime sky and their movements but really, they don't mean anything. Venus isn't the embodiment of love, Mercury isn't spirit and Jupiter doesn't represent leadership any more than my shoes do.

What they are however, are wondrous other worlds that share our solar system with us. Seeing them is a thrill just because they're there. Excuse me while I geek out on some astronomy.

I can't help but wonder what it's really like on those other worlds when I see them. Here's Jupiter, the largest planet in our solar system.

photo from NASA

It's what's known as one of the gas giants in that it has a tiny rocky core surrounded by hydrogen and helium and a handful of other elements. Its size is mostly gas and that's kind of hard to imagine. Jupiter is massive and this spliced together photo shows it in relation to the size of the Earth. Jupiter has at least 64 moons and the largest of them, Ganymede, is larger than Mercury.

photo from NASA

Simply amazing.

Here's Venus.

Image processing by R. Nunes

Venus is the second planet from the sun and is 20 percent smaller than the Earth. Its size has earned it the reputation as the Earth's sister planet. The similarities end there though. Its surface is permanently obscured by dense clouds of sulfuric acid floating in an atmosphere composed primarily of carbon dioxide. Penetrating radar has shown Venus to have a bone-dry, rocky surface punctuated by some very serious volcanoes.

Finally, here's Mercury.

photo from NASA

Mercury is the planet closest to the sun in our solar system. It's also the smallest of the planets orbiting our sun. It has a molten iron core and a surface composed of silicates primarily. Its surface is pockmarked with craters and appears to lead a pretty tough existence. Its proximity to the sun gives it some amazing temperature variations. During the day, the surface temperature can reach 840 degrees F (450 degrees C) and at night the temperature drops to -275 degrees F (-170 degrees C). Talk about freeze thaw cycle.

These three planets have been observed by human beings since the dawn of our species and until the last few hundred years, no one knew what they were. Living in an age when understanding the planets is a Google search away is an amazing thing. Knowing that Jupiter's made of gas primarily and that Venus exists under a veil of sulfuric acid clouds and that Mercury experiences such wild temperature fluctuations every day fires my imagination more than any myth ever could.

So over the next few weeks, look west just after the sun sets and be treated to one of the greatest shows in the solar system.


  1. I'm so fascinated by astronomy. I really need to learn how to use my telescope properly! A few years ago, I was able to see Saturn with it. It was small and fuzzy, but I could definitely make out the rings.

    Really interesting post, Paul - I had no idea Mercury gets so hot & cold!

  2. Thanks Kelly, I was thinking of you and the rest of my Canadian friends when I did the Celsius conversions.

  3. Great entry, Paul! Took an astronomy class waaaaay back in college and loved it. Thanks for the refresher and for reminding me to look up every once in a while and enjoy the dance that surrounds us.

  4. Thanks Angel! I love your phrase, "The dance that surrounds us." Mind if I borrow it?


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