Posts Tagged ‘comets’

Phaethon Cometh

Posted: 7 December 2007 in Uncategorized
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One of the dark horses of the inner solar system makes its closest approach to Earth since it was discovered in 1983 soon.  Phaethon is an asteroid (perhaps the burnt out core of a comet).  We pass through its debris trail every December, resulting in the Geminid meteor shower.  This year, the Geminids will peak on December 13-14th.  Bonus:  the Geminids are likely to be even better than the Perseids this year.  Unfortunately, it’s cold out.  Plus I have an exam on the 14th.  This meteor shower didn’t get the memo I sent out that it had to fall on a weekend.

So what’s special about the Geminids?  Phaethon is a source of denser meteors than are found in most other meteor showers.  This results in meteor paths that can be jagged and more meteors that break apart and split.  According to, the Geminids have a history of slow, bright meteors and faint meteors, but few medium-brightness ones.  The moon will be a faint crescent and peak times will see 60-120 meteors per hour.

For more on the discussion of whether Phaethon is a burnt out comet or an asteroid, check out Astroprof’s page on the topic.  If you happened to download Celestia when I talked about it before, you can also download an add-on that includes a few thousand near-Earth objects.  Phaethon is included in that pack (it doesn’t come with Celestia by default, or at least I couldn’t find it).  That site (the Celestia Motherlode) has a number of very awesome additions to Celestia, so I recommend checking it out.


Leonid Meteor Shower

Posted: 16 November 2007 in Uncategorized
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This weekend will be the peak time for the Leonid meteor shower. It is so-named because the meteors originate from the section of the sky corresponding to the constellation Leo. The most locateable star in Leo is Regulus, which rises these days just after midnight on the eastern horizon. A little while later, Saturn rises behind it. Saturn and Regulus are both fairly bright so they make an easy pair to spot. The sky map below is from a perspective of Pittsburgh, PA at 1:51 am tonight (November 17, 2007). Peak time for the shower will be around 4am tonight and tomorrow night. [source]

Of course, you don’t have to find the constellation Leo in order to enjoy the Leonids. The comet Tempel-Tuttle leaves a trail of dust as it orbits the sun and occasionally we stray right into it. In 1833, the event was so huge people from Europe and North America took note of it. Estimates of the storm activity put it at over 200,000 meteors per hour! I dream of such a thing. It even led to the song “Stars Fell on Alabama.” Another big storm occurred in 1866 and again in 1966. Unfortunately, it looks like this year will be a modest viewing year, which puts the Leonids lower on the totem pole than the Perseids, which occur back in early August.

Viewing conditions for Pittsburgh look grim, which is typical of this time of year. This morning we had our first real snow. It had snowed a week or two ago briefly, but that was more of a snowy drizzle/wintry mix. Today there was actually accumulation on the dead leaves in the yard and on some cars. Nothing major yet.

The constellation Leo with Regulus and Saturn, where the Leonid meteor shower originates