Looking Up: One More Time...

Aug 20, 2018

Comet Giacobini-Zinner was discovered on Dec. 20, 1900 by Michel Giacobini at the Nice Observatory in France.The debris stream from this dirty spaceball results in an annual meteor shower: the Draconids, which take place each year in early October.
Credit N.A.Sharp/NOAO/AURA/NSF / nasa.gov / earthsky.org

On this week's Looking Up Hal points out the meteoric rise of GZ (short for comet Giacobini-Zinner) a celestial visitor visible in the Colorado sky this month.

Comets, you recall, are often called dirty snowballs in space. They are made up of the original materials from the formation of the solar system, and thus are some of the oldest things out there. Trillions of comets slowly circle the Sun way, way out there, many times farther than Pluto, in a cloud of comets known as the Oort Cloud. Some of these comets will never fall in toward the inner-solar system, and others will drop by and then zip away for thousands, or even millions of years.

But there are some comets that are, well, local. This group includes GZ, which orbits the Sun once every 6 ½ years or so. This hunk of stuff is about 2 km or so across, about a mile and a quarter, and when it rounds the Sun, the solar winds blast the surface of the comet and blow out a long tail of debris. When the Earth’s orbit happens to intersect this path, we get meteor showers. GZ’s meteor shower happens in October and traditionally produces a pretty weak meteor shower. But every so often, most recently in 1933 and 1946, we hit the debris tail just right, and observers saw several thousand meteors per hour. Will we get lucky this October 9th? We can’t know ahead of time, but take a look at the comet now, and get ready in October, because it just might be awesome!

If you’d like to take a closer look at Comet Giacobini-Zinner, or any of the other wonderful and amazing things in the sky, please visit csastro.org for a link to information on our monthly meetings and our free public star parties.