Greetings, stargazers.
I hope you enjoyed the lunar eclipse more than doing your taxes. If you missed this one, there are more to come in the next couple of years. The next one happens Oct. 8.
Eclipses this year are exceptionally unusual in that there are lunar eclipses and solar eclipse in the same month, not just once, but twice. But to see the April annular solar eclipse you will have to be in Antarctica on Tuesday for the brief 49-second event.
This month
Jupiter and the four Galilean moons, now high in the west after sunset, are always great targets in binoculars or a small telescope. Because of the current alignment, eclipses and transits of these moons are frequent. For example, the moon Io orbits Jupiter every 42½ hours, so in that time span there will be one eclipse and one transit.
An eclipse is when the moon passes behind Jupiter, and a transit happens when a moon passes in front. Both can be seen easily in binoculars or a small telescope, but you will need a telescope to see any details. During a transit, the shadow of the moon appears as a dark spot on the surface of Jupiter and is actually much easier to see than the moon itself.
The link below is a useful online predictor of where Jupiter’s moons will be at any specified time. Check the calculator to see if the next event will occur during the few hours Jupiter is up in the evening.
Right now, Mars and Saturn also make great evening targets for observation. Mars is in the constellation Virgo, and Saturn is in Libra. Both are as close as they will get this year. At its closest approach a couple of weeks ago, Mars was overhead at midnight, but that is a bit too late for many armchair astronomers. Saturn makes its closest approach May 10, so that is when it will be highest at midnight. During the next few months both will be higher and higher earlier in the evening and therefore more convenient to see.
Being at its closest also means these planets are in the middle of their retrograde motion as the Earth passes them up in its orbit around the sun. Mars, Jupiter and Saturn typically move from west to east against the background of stars. But when the Earth is passing one of them, there is a brief time when the path of the planet appears to change direction and head east to west. That is what is happening right now for Mars and Saturn.
Activities with the Four Corners Stargazers should be heating up with the weather. The summer plan is to try to meet somewhere every clear Friday night for some sort of observing activity. Regular summer new-moon events are always scheduled at the Durango Nature Center, and Durango Discovery Museum has at least one evening of stargazing June 7 to cap off Animas River Days.
Charles Hakes is an assistant professor in the physics and engineering department at Fort Lewis College and is director of the Fort Lewis Observatory. hakes_c@fortlewis.edu.
Useful links
Jupiter’s moons calculator: www.shallowsky.com/jupiter/
Retrograde motion of Mars: http://mars.jpl.nasa.gov/allaboutmars/nightsky/retrograde/
Four Corners Stargazers: http://groups.google.com/group/Four-Corners-Stargazers
An astronomers forecast for Durango: www.cleardarksky.com/c/DrngoCOkey.html?1
Old Fort Lewis Observatory: www.fortlewis.edu/observatory
