Tehachapi Skywatch
Tehachapi Skywatch: Comet bursts forth from out of the darkness
By: Dale Hawkins
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Posted by editor Tue Nov 30, 1999 00:00:00 PST
Viewed 166 times
0 responses 0 comments Comets have always fascinated sky watchers — and until recently, terrified them.
These huge, dirty snowballs come from the furthest reaches of the Solar System, plunging toward the sun. Rarely do they hit the sun; they make a close pass and swing around the other side, heading back into deep space, perhaps to return in another few million years. However, some have their orbits changed by passing too close to a planet and return every few tens, hundreds, or thousands of years.
Comet Halley is the most famous of these “periodic comets,” being the first whose return was accurately predicted.
Earlier this year, the astronomical community was energized by the sudden appearance and passing of Comet McNaught. Unfortunately, it quickly passed to the southern hemisphere, leaving us northerners to view images on the Internet.
Now it's our turn to view a dazzling comet. Comet 17P/Holmes (read as, the seventeenth periodic comet to be discovered; discoverer: (Edwin) Holmes) brightened nearly a million fold in a matter of hours. On Oct. 22 it was a seventeenth magnitude comet requiring a large telescope to see. (Sixth magnitude is the limit of the unaided human eye.) Three days later it had reached second magnitude and easily caught the eye of anyone who is familiar with the constellation Perseus. It was still as bright on Oct. 31.
As I mentioned, the comet is in the constellation Perseus just to the left of Xi Persei. At about 8 p.m., that places it in the northeast about 30 degrees above the horizon (one-third of the way up to the zenith). It will be nearly directly overhead by about 2 a.m. It is easy to recognize (if it is still bright) because it is noticeably fuzzy compared to the pinpoint of starlight. However, don't expect to see a tail. The comet is almost directly opposite the sun, which means the tail is streaming almost directly away from us.
To the unaided eye, it's just a fuzzy star. However, binoculars will show its distinct “snowball” appearance. With a telescope, you should be able to see the nucleus as a bright pin-point just off-center of the “snowball.” The comet is presently 150 million miles (245 million kilometers) away from earth, or about 1.6 astronomical units (the distance from the earth to the sun), so don't worry about this one hitting us.
The comet was first discovered in 1892 when it had a similar outburst and faded by three magnitudes over the course of a week. I regret that it may have faded from sight by the time this article goes to press; but I'm willing to bet it will still be visible to the naked eye.
Manned Space Watch
After having attached “Node 2” to Space Station Alpha, which will allow the attachment of more modules in the coming months, Discovery commander Pam Melroy is scheduled to guide the ship to a touchdown at the Kennedy Space Center on Wednesday, Nov. 7, at 2:13 a.m., Tehachapi time.
Space Probe Watch
The Chinese have launched their first space probe to the moon. Named Chang'e 1, after a legendary Chinese goddess who flew to the moon, the probe will orbit the moon and send back photographs. The probe was launched only weeks after a similar launch by Japan. India is expected to follow suit in April in what is being called by some as an “undeclared Asian space race.”
Night Sky Watch
With a new moon on Friday, we will have dark skies.
Jupiter is still bright in the south western sky.
Mars rises before midnight and is becoming more spectacular and colorful as we approach opposition on Christmas Eve.
Venus is still dazzling in the morning sky.
Mercury reaches greatest western elongation (its highest point in the eastern, morning sky) on Thursday.
Ceres, the largest asteroid, reaches opposition on Friday and can be found perched on the tail of Cetus, the whale. The Dawn space probe is on its way to Ceres via Vesta.
Sunrise/Sunset (PST)
6:21 AM/4:53 PM
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