The Astronomy Nexus is a personal website covering all sorts of topics on astronomy and other interests.

What a long strange trip it's been

I haven't posted a whole lot of updates in the last year. That's because I've been busy with something else huge: adopting a beautiful 6-year old girl from China.

As you can imagine, this has kept me pretty busy, so this site's been pretty quiet. More pictures below...

In the Doghouse?

Pluto the dog

You've probably heard the news a few days ago that astronomers came up with a new definition for "planets" that added 3 new planets to the solar system (including the largest asteroid, Ceres). A couple days ago, another definition was proposed, which appears to be more consistent in some ways. However, it excludes the farthest traditional planet, Pluto. By and large, professional astronomers don't care too much one way or the other -- reactions like this (Rob Knop) and this (Phil Plait) are pretty typical. In general, what a "planet" is matters more to the general public than to the pros.

Even given that, you do have to wonder what the fuss is about. It's pretty clear nowadays that Pluto is a very small object, different from the other 8 traditional planets. In fact, Pluto is more like the largest non-planetary bodies in some ways. Pluto is about a dozen times more massive than the largest asteroid (Ceres), but the smallest remaining planet, Mercury, is more than 20 times more massive than Pluto. Seven satellites (our Moon, the four large moons of Jupiter, Saturn's moon Titan, and Neptune's moon Triton) have more mass than Pluto. If Pluto had been discovered yesterday, or even 20 years ago, rather than almost a century ago, it almost certainly would not have been called a planet at all!

So why was Pluto ever considered a planet in the first place, rather than something like a really large, icy asteroid? It turns out there is a lot of interesting history behind this, involving a couple of great planet hunts in past centuries. More below.

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Today's Deep-Sky Objects: Markarian's Chain

If you're a Northern Hemisphere observer, you'll notice that at this time of year, the Milky Way isn't visible. In fact, during late-spring evenings the Milky Way roughly circles the horizon -- almost impossible to see even on a dark night -- which means the sky overhead, or close to it, is as far from the Milky Way as possible.

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Deep-Sky Object of the Week: M3

As spring in the Northern Hemisphere begins to blend into summer, the night sky changes as well: the huge galaxy-rich fields of early spring skies begin to drift down towards the west, and the objects closer to the Milky Way become more prominent. The late spring and early summer sky is full of an interesting type of object: globular clusters, huge balls of stars held together by their own gravity, orbiting the entire Milky Way galaxy.

Welcoming visitors and comets

I have recently updated this site to use a new content management system. This should make it a lot easier to find things, make site updates, and use this site as a record of observations I make. I have kept all the material from the old version of this site, so it should be possible to find old favorites.

Recently, I welcomed Comet Schwassmann-Wachmann 3 (a.k.a. Comet 73/P Schwassmann-Wachmann) into my back yard. As you may know, this comet has fragmented, rather like Comet Shoemaker-Levy 9 which hit Jupiter in 1994. There are currently dozens of fragments, in a huge range of sizes. The two largest fragments, "B" and "C", are easily visible for the next few weeks in small telescopes, and one or two of the others are in range of really big amateur scopes.

Last night I saw both of the large fragments in my small refractor (100mm, f/6 -- nice wide field views). Fragment "B" was a little easier to see -- I think it's more condensed, and so has a higher surface brightness. This was especially important with an almost-full Moon not far away! More details below...

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