One of the jokes I inherited from my student years is the final exam question "Describe the Universe" which was followed by "and give two examples."

If you visit the Public Observatory during its daytime hours in May (1–3pm on Wednesday through Saturday, weather permitting), you can use the 16” telescope to observe an object which looks a lot like the Moon.  Hanging in a blue sky, it shines with yellowish reflected sunlight. 

We are all familiar with the climate on Earth: the seasons, the range of surface temperatures that are just right for being a water world, the oxygen we breathe, the ozone layer that protects us from UV radiation. In short: habitable. So what other bodies in the Solar System might be (or might have been) habitable, and why aren’t they today? Mars probably comes to mind, and for good reason. Mars has the most similar climate to our own, with water ice caps at the poles, seasonal snow, and dust storms. This is because Mars has a similar axial tilt as the Earth, which creates similar seasonal temperature variations.

For the month of June, 30 beautiful images of the solar system are on display on the terrace by the Independence Avenue entrance.  They are part of the From Earth to the Solar System exhibition developed by the Smithsonian Astrophysical Observatory/Chandra with the NASA Astrobiology Institute.

Today at 8:45 pm EDT (March 18, 2011, 12:45 am UTC), MESSENGER will become the first spacecraft ever to enter Mercury's orbit. With MESSENGER on the last leg of its journey, I’m reminded how long it has taken to get there.  I watched the spacecraft launch in the early morning hours of August 3, 2004, almost six and a half years ago.  Now after one flyby of Earth, two flybys of Venus, and three flybys of Mercury, the spacecraft will catch up with Mercury again, but this time it will be captured by the planet.  You might think as one of our closest neighbors in the Solar System it would take a lot less time to get into Mercury orbit – but because Mercury is the closest planet to the Sun, at a distance where the influence of the Sun’s gravity is much greater, it is a challenge to reach and orbit.

I first thought of putting together a book on planetary tectonics when I was working on a general subject matter book on the planets in the mid 1990’s.  That book had a “comparing the planets” section where I showed examples of tectonic landforms on Mercury, Venus, Earth, and Mars.  Tectonic landforms are created when forces act on solid crustal material and they are found on objects of all sizes in the solar system.