Science

Physics, Aerospace, and General Science

Fascinating!

Posted by Tom on January 20, 2008
Posted in: Astronomy, Radio.

Early this morning (01/20/08) I took part in a fascinating radio test, the HAARP – LWA Moon Bounce Experiment It was an attempt to detect high frequency (~7MHz) radio waves reflected from the Moon using regular amateur radio receivers and antennas.

I was quite skeptical of the possibility but still got myself out of bed at 0630z (0030 am CST) to see for myself. The experiment was to last for two hours, one hour on 6.7925MHz and the next hour on 7.4075MHz. Fellow hams will notice that these frequencies are just below and above the 40 meter amateur band, an extremely low frequency for Moon bounce.

The tests consisted of 2 seconds of transmission followed by 3 seconds of silence with this pattern repeated for one hour on each frequency. Since the round-trip travel time for the signal to reach the Moon and return is about 2-1/2 seconds, the echo should occur in the silent period. You can read the other details of the experiment at the link above.

The bottom line: Even with my modest antenna (a multi-band vertical) I was able to hear the signal returning. Not strong, but easily audible. I was really surprised when I first heard the echoes. Even with the transmitter putting out 3.6 megawatts of RF power, I felt it was an amazing feat.

I’ve submitted my report to the people at HAARP and I’m pleased to have made even a tiny contribution to the experiment.

Lunar Eclipse 08/28/07

Posted by Tom on August 28, 2007
Posted in: Astronomy.

I promise I’ll finish up the Alaska posts Real Soon Now, but I wanted to show this picture of last nights Lunar eclipse. Here is a shot taken at 04:59 CDT August 28, 2007, just after totality began. The moon was quite low on our western horizon so I didn’t get to see it at mid-eclipse.

I’m not sure why but this turned out to be one of the darkest eclipses that can I remember.   I know several people who said they were looking around the time this was taken and didn’t see it.

Lunar Eclipse

Photo details: exposure 1.3 second at f/5.6, ISO 1600 and F.L. 300mm.

Moon-Venus

Posted by Tom on May 20, 2007
Posted in: Astronomy.

We had this beautiful view in the western sky last night.

Moon and Venus

The brilliant (magnitude -4) planet Venus was approximately 1 degree from the 3.5 day old crescent Moon. The photo doesn’t do justice to the entire view with the Moon in the constellation of Gemini, crowned by the two bright stars, Castor and Pollux.

The image above is a cropped portion of a picture taken with a Nikon D80 using a 70-300 zoom lens at 300mm focal length. Exposure was 1/125 second at f/5.6 and ISO 1600.

Next month, on June 18, there will be a similar configuration with the added feature of the planet Saturn also being near the moon. If you have a good place to observe the western sky and your weather cooperates, this should be a spectacular sight. Mark your calender and look shortly after sunset.

Stars in Winter

Posted by Tom on January 7, 2007
Posted in: Astronomy.

Last night we had one of those winter nights with crisp clear transparent skies. I decided to try my hand at photographing the sky with my new camera. The picture below was taken January 6th at 18:56:36 CST. It was a 30 second exposure at f/3.8, 20mm FL and ISO 1600.

Orion S
To see a larger image, click here

In the picture, the constellation Orion is just rising from behind the trees at the bottom and Taurus is near the top of the picture. You can see just a hint of the nebulosity around M42 in Orion’s sword.

I’ve still got a lot to learn about this sort of photography but I’m fairly happy with this early attempt. I’ll be trying again on the next clear, moonless night.

Leonid Meteors

Posted by Tom on November 11, 2006
Posted in: Science.

LeonidThe Leonid meteor shower occurs every year between November 14th and 21st with the peak usually on the 19th. They are called the Leonids because they appear to radiate from the constellation of Leo. This shower has a history of occasionally producing spectacular displays called meteor storms. A few years ago I watched the Leonids and, for a short while, saw more meteors than I could count.

This shower is extremely variable so it’s hard to predict numbers, but there is always a chance of another intense shower. Also, this year the moon will not interfere with visibility of the fainter ones.

The peak will occur at approximately 10:45PM (CST) which is near the time Leo is rising here in Iowa. People farther east may have a better opportunity as it will be higher in the sky during the peak.

Because of the low altitude of the radiant point, there is also a chance of earth grazing meteors which just brush the Earth’s atmosphere and then skip back out into space. If you don’t have a clear eastern horizon, you can wait several hours after the peak time (as Leo rises higher) and still have a good chance of seeing a number of meteors.

If you are interested in trying to watch the Leonids, this link will provide more information. If you go out and do see some meteors, please post a comment on what you observed.

Occultation

Posted by Tom on October 8, 2006
Posted in: Science.

Moon and Pleiades In astronomy, an occultation is when one closer object passes in front of another farther object. Most commonly, our Moon is the closer object and a star or planet is the more distant one.

Tomorrow night (October 9 in the US) you’ll get to see this phenomena for yourself. Starting around 11pm CDT (4am GMT on the 10th) the nearly full Moon will pass in front of the Pleiades star cluster (Messier 45) in the constellation of Taurus. The stars of this cluster will disappear behind the bright edge of the Moon and reappear later from the dark edge.

Because of the brightness of the Moon you’ll need binoculars or a small telescope to see this best. It’s rather amazing to see the stars pop out almost instaniously from behind the dark limb.

At my location the Moon will rise around 8PM so it will be well above the eastern horizon by the time the occultations begin. You can check your local paper for the time of Moonrise in your area. If you click on the thumbnail you can see a timeline of the Moon’s position relative to the star cluster. This chart is only strictly valid for my location (Central Iowa). If you want to get accurate information for your own location you can go to this link for details. Otherwise, just go out and look up at the sky around the times indicated (adjusted for your time zone.)