Mark Sachs (ksleet) wrote,
Mark Sachs

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You thought that I would need a crystal ball to see right through the haze?

So I was messing around with Celestia, the all-singing all-dancing space simulator, as I am wont to do lately. While looking at the extrasolar planets through the Star Browser I noticed that it is missing the most distant extrasolar planetary system (or at least the most distant we have real confidence in), OGLE-BLG-235. So, I decided to add it.

Adding stuff to Celestia isn't too hard, as long as you keep in mind the important fact that the user-created add-on documentation, where it exists at all, is so out of date as to be actually counterproductive. So ignore it and instead read the .ssc and .stc files that come with Celestia to see how you set up stars and planets -- they're all text files, so it's not too difficult as these things go. The star OGLE-BLG-235 was not in Celestia, which is unsurprisng considering that it was only detected as part of the gravitational lensing event that also let us detect the planet. So, I had to add a simple .stc file which specified the star's right ascension and declination, distance from Earth, and spectral type. Next, the planet had to be added with a simple .ssc file. Virtually nothing is known of this planet beyond its mass and its distance from the star at the time of the event, and nothing can be known because gravitational lensing depends on a chance alignment of stars and it's ridiculously unlikely to ever recur. So, I put in default values similar to the other extrasolar planets.

Iterate through a couple passes of "why won't this stupid thing work?" which led to my conclusion about the documentation above, then cruise out there, spin the time clock forwards and backwards until the view is nice, and Bob's your uncle.

This view is looking back towards the Sun, which is highlighted with a green marker since it is invisible at such a distance (not too shocking as OGLE-BLG-235 is much farther away than almost any other star currently in Celestia, about 17,000 light years.) Only especially large stars visible from Earth, such as Deneb to the upper right, can be seen here. In fact, since the stars known to Celestia are centered around the Sun, looking in any other direction from OGLE-BLG-235 B is rather lonely.

(Did I mention that this place is really, really far away? OGLE-BLG-235 is the red marker, the Sun is the green one.)

The add-on is here if you want to try it. Just unzip it into Celestia's Extras directory and that's it, really. You can find the place through the Star Browser or just hit enter and type the star's name to select it, then press G to go there.

Oh, while I'm on the subject: I hadn't known until today that Celestia has a "Go to Surface" command (CTRL-G) allowing it to be used more like traditional planetarium software. You can also adjust the field of view dynamically, which is essentially the equivalent of a telescopic view. Of course, this being Celestia you can go to the surface of any planet or other astronomical body you please, so I went to the surface of Mars and snapped an 800x daylight picture of the Earth and Moon.
Tags: science
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