The Galilean Moons

In the year 1610, it was commonly believed that the Earth was the center of the Universe, that all bodies rotated around the perfect planet, placed by god with the heavens around it.  Galileo Galilei dealt a major blow to this idea, by using an early telescope to improve his vision and look up at some surprising dots. These dots formed a line that went straight through the bright planet Jupiter.  As Galileo looked again and again, night after night, he noticed that they not only persisted, they moved.  Their motion was predictable, and Galileo realized that they were orbiting Jupiter, just...

Europa Chemistry

I always get giddy when talking about Europa, as many astronomers do.  It’s one of the most fascinating places in our solar system when it comes to the search for life.  It has lots of water, likely contained in a subsurface ocean.  It’s heated though a gravitational tug of war with Jupiter and the other Galilean moons.  And, as of recently, it has a chemical production system that matches Earth’s. I wonder what goes on beneath the thick ice of Europa.  Is there an ecosystem filled with alien life down there?  Life in Earth’s oceans feels very alien, but creatures from...

1000 Things You Didn’t Know About The Universe #6: Earth’s Moon is Big

When we see the Earth’s only Moon up in the sky, we often think about how small it is.  It’s only about 1/4 the diameter of the Earth, and at a distance of 384,000 Km, it looks small in the sky.  But often size is entirely a matter of perspective.  What we compare something to, that’s what determines it’s size.  When the Moon is high in the sky we easily compare it to the size of the window we are looking through, or to a nearby tree, or our outstretched hand.  All of this can make the Moon seem pretty tiny....

Four Moons Larger than Luna

Our Solar System is so much more than just the eight planets that inhabit it.  One of the things I learned a bit later in my career as an astronomer (my teenage years; been doing this for awhile) is how unique and diverse the natural satellites are.  Our own moon seems somewhat tame, and it’s easy to think the same of all moons.  Many of them are boring quiescent rocks with little more scientific value than asteroids, but the largest hide deep and profound secrets that we are just starting to unlock.  Four moons in our solar system are larger...

A Song to laugh about the 176 Moons of the Solar System

About a year ago I had an idea for a music video.  I wanted to take a concept in science and put it to music, making it funny, catchy, memorable, and educational.  I wrote out the majority of the lyrics but left it alone for a few months, until I connected with the right friend.  My good friend Bob Wegner is a very talented guitarist and audio engineer, and as we spoke about the idea he wanted to be the guy to record it.  We spent an afternoon doing the vocals and guitars, and he cleaned it up and made...

Do You Weigh Less When the Moon is Above You?

Everything in the universe that has mass, has gravity.  It’s easy to understand that the Earth has gravity and pulls on us all day every day.  It’s just as easy to understand that the Moon and the planets and the Sun have gravity too, and they are all pulling on us. It’s much harder to understand that every person on Earth has gravity too.  You exert a force on the Earth, and on every other human.  You also exert a force on every rock, tree, and creature that roams the Earth, and they all exert a force on you.  The...

Jupiter’s Triple Moon Eclipse and Ceres Comes Into View

There has been a lot to talk about with our home solar system lately.  Spacecraft approaching dwarf planets, robots on Mars, and all kinds of orbiters giving new insights and views we had never expected.  It’s a heavy news year for Planetary Science, and the great stories keep creeping up! Today we have an update on the Dawn spacecraft approaching Ceres.  The picture I posted on January 20th  (shown below) was from 380,000 Km away, comparable to the distance between Earth and the Moon. Now, about 2 weeks later, Dawn is only 145,000 Km away, and the view is much clearer!...