Planets in the spotlight

The Mars opposition has passed but the planet is still holding forth in the eastern sky a couple of hours after local sunset. Normally opposition is also the date the planet is closest to Earth, however, due to the vagaries of orbital mechanics -- I don't pretend to understand it, I just report on it -- Mars will be at its closest for this pass on Monday, May 29.

It has to do I think with the fact that planetary orbits are oval and not perfect circles.

In any case, Mars is in a fine position for viewing at least for the next two weeks. Look in the southeast just above the horizon. Mars is in the head of the constellation Scorpius.

There are two other bright objects in the area, just below Mars and slightly left is Antares, the Heart of Scorpius. Antares is often mistaken for Mars because they both are a bright reddish color. A good way to tell them apart is to remember, stars twinkle, planets don't. You can check it out for yourself.

The other bright object to the left of Antares is the planet Saturn, the three of them make a nice triangle in the sky. On June 3, Saturn will be at opposition.

This is a fine time for planet viewing, in addition to our two main attractions, the planet Jupiter is still making a very bright showing in the southwestern sky,

Jupiter makes a fine telescopic subject especially with its four Galilean moons being quite prominent. Tonight, Wednesday, May 25, all four moons are visible. Ganymede and Io to the left of the planet and Europa and Callisto to the right.

Just remember the moons change position each night so they won't always be where we think they are. Astronomy Magazine--the print version--has a monthly chart of where the moons will be.

If you have access to a very clear, unobstructed eastern horizon there will be a very slight opportunity to catch swift Mercury when it reaches its greatest western elongation on June 3. Unfortunately, the plane of the ecliptic is very shallow so it will not gain much altitude.

However, we will have a very handy helper, a very slender crescent moon will be very near the planet. Be looking east about a half-hour before local sunrise. Since the moon is just a few hours from being new, the crescent will be very, very slim.

The tiny dot of Mercury will be just above the moon, binoculars will be essential as both objects will be in the same field of view (FOV). Happy hunting on this one.

There are two more planets in our sky at this time, Uranus and Neptune, and as always both very difficult to locate without some help. Once again our handy, dandy, moon will come to our aid.

Sunday, May 29, the moon and Neptune will be above the southeastern horizon. Start looking at least by 0300 MDT. Both will be in the same binocular FOV. Place the moon at 2:00, and the planet will be at about the 8 o'clock position.

Wednesday, June 1, our friendly moon has moved on to now show us the other distant gas giant planet Uranus. Both are in the same FOV with the moon at 4 o'clock and the planet will be at 10 o'clock.

SKY WATCH: Third quarter moon, Sunday, May 29.

NEXT WEEK: Saturn's turn in the spotlight and more astronomical blathering.