February: Satellite Watching

February 2010

Satellite Watching

By Calvin L. Chrisman

Last month I spent an evening satellite watching with some friends in an open field in Black Mountain. This is naked-eye astronomy that is easy to do and it is quite interesting. Within about an hour, we were able to see an Iridium satellite flair brightly and the International Space Station, with its crew of six, pass overhead. The sixty-six Iridium satellites are used for satellite telephone services and have very reflective solar panels that create bright flashes when in the right position. They can reach -9.0 magnitude which is extremely bright. The full moon is -12.6 and Venus at its brightest is -4.6 (remember lower magnitudes are brighter). An Iridium flair lasts only a short few seconds, but is impressive to see. A visible pass of the ISS, on the other hand, lasts from two to five minutes. You might confuse it with an airplane, but it will not have any navigation lights (very limited traffic 225 miles up).

So how can you try this for yourself? Simple – go to the website www.heavens-above.com which is dedicated to tracking and providing information on satellites, comets and other things in the night sky. It will need your location, which you can pick from a database (BlackMountain is there) or, if you know your latitude and longitude, you can enter these manually for more accuracy. You can get these coordinates by going to Google Earth and putting your cursor over your house. After you enter this information, you can click for visible passes of the ISS, the Hubble Space Telescope and others as well as for Iridium flairs visible at your location. The website will then provide you with specific times for the flair, or rise, peak and set times for satellite passes along with compass bearings and altitudes above the horizon for the event. Make sure to set your watch accurately, because the times are specific and the events don’t last long. Satellite passes usually are shown to begin at 10 degrees above the horizon. Remember that this assumes you are a “flatlander” and our mountains may be in the way for a while. Just scan the sky in the right direction and you will soon spot movement. If the satellite pass you are looking for is listed to end at a higher altitude than about 10 degrees above the horizon, you will see an interesting phenomenon. The satellite will disappear by entering the Earth’s shadow. It will slowly fade and then go out before it reaches the horizon.

While we were satellite watching, we also took time to look at the Pleiades, an open cluster of blue stars near Taurus the bull. Six or seven stars are visible to the naked eye, and with binoculars, over fifty are visible. It is a striking sight. The final sight for our viewing was Mars, which is just past its closest approach to Earth. It continues to be bright orange in the early evening sky. You may have read recently that the Mars rover, Spirit is being re-defined as a fixed observatory. It has been stuck in loose sand and two of three wheels on one side are broken. Spirit has shown a lot of, well, spirit. Its original mission was to last three months and it is entering its seventh year of service. NASA is now trying to reposition it to get maximum sun on its solar panel as winter begins in Mars’ southern hemisphere. If its batteries and electronics can survive the cold, Spirit will continue to provide scientists with data in the future. Let’s hope Spirit doesn’t give up the ghost.

A final note, toward the end of the second week of February, look toward the west and you will see the two brightest planets in close proximity, reaching their closest on the 16th. Jupiter is leaving our evening sky and Venus is just moving back into view from behind the Sun. They will only be visible near sunset (a little after 6:00) and will be low in the sky, but the proximity will be striking and well worth a search.

Clear Skies!

Leave a Comment