Astronomy columnist explains why it's hot in July, why we can see satellites with the naked eye and why the North Star isn't the brightest among other topics.
?| November 14, 2011?|
A mountain top above the clouds and light-polluted cities of Romania served as a good spot from which astrophotographer Alex Tudorica could watch the 2008 Perseid meteor shower. This composite picture from one of the highest points in Romania, the Omu summit (2,507 meters) in the Southern Carpathian Mountains, captured about 20 of the shower's bright streaks.
Image: Alex Tudorica/Argelander Institute for Astronomy
With the return of the brilliant planet Venus to our evening sky, I'm reminded of an amusing anecdote related by a good friend of mine, George Lovi, a well-known astronomy lecturer and author who passed away in 1993.
One night, while running a public night at the Brooklyn College Observatory in New York, the telescope was pointed right at Venus, which was displaying a delicate crescent shape at the time. Yet, one student gazing through the telescope eyepiece stubbornly insisted that he was really looking at the moon. When George pointed out that the moon wasn't even in the sky, the student replied, "So what? Doesn't a telescope show you things you can't see without it?"
That story got me thinking about a number of popular misconceptions in astronomy. Here's my own personal list of ten, in no particular order:
1. Why don't most meteor showers "shower?"
When an announcement is made through the news media about an upcoming meteor shower, it likely will conjure up visions in the minds of many of a sky filled with meteors pouring out of the sky like water from a hose.
Unfortunately, in just about all cases, your average meteor shower is a far cry from that. Typically, if you're outside on a clear, dark night you might catch a glimpse of perhaps three to six meteors (popularly called "shooting stars") over the course of an hour's watch.
On certain nights, the hourly rate may be somewhat higher, in which case astronomers would say that a "meteor shower" is in progress. In the middle of August or the middle of December for instance, you might notice that meteors are comparatively plentiful; perhaps coming at a rate of about one per minute. Indeed, these are the times of the two best meteor displays of the year, although it would never occur to you that a "shower" was in progress. [2011 Orionid Meteor Shower Photos]
There are rare occasions, when Earth interacts with a dense trail of dust recently shed by a passing comet, and meteors will seem to literally pour from the sky in a shower-like fashion. Unfortunately, such opportunities are few and far between. On May 31, 2022 however, we just might get a chance to witness a true "storm" of meteors, with potential rates of thousands per hour. On that night, Earth might pass through the dusty debris that was shed by a comet that broke apart into several fragments in 1995.?
2. Can artificial satellites really be seen with the unaided eye?
Most definitely! In fact, many people are surprised that an object orbiting hundreds of miles above our heads can be readily seen without the use of binoculars or a telescope. From the launch of the first satellite, Sputnik, in 1957 to the present, the number of satellites in space has grown at a spectacular rate. There are now over 10,000 satellites orbiting the Earth.
British astronomer Desmond King-Hele once noted that a satellite, "looks like a star that has taken leave of its senses and decided to move off to another part of the sky."
If you go out and carefully study the sky near dusk or dawn, the odds are that you should not have to wait more than 15 minutes before you see a satellite now in orbit. Most are too faint to be seen with the unaided eye, but a few hundred are large enough and low enough (100 to 400 miles/160 to 640 kilometers above Earth) to be seen. [Photos: Spotting Satellites & Spaceships from Earth]
Source: http://rss.sciam.com/click.phdo?i=cab4b8c0d0d3835c501ab6e0e4a24ad5
matt moore matt moore national grid andrew luck andrew luck day light savings time 2011 hocus pocus
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.