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Mercury Transit of Sun on Nov. 8

A Once-In-7-Years Event

By Lewis McCool

Moon Phases

•  First Quarter: Nov. 27, 11:29 p.m.
•  Full: Nov. 5, 5:58 a.m. (Beaver Moon); Dec. 4, 5:25 p.m. (Cold Moon)
•  Last Quarter: Nov. 12, 10:45 a.m.; Dec. 12, 7:32 a.m.
•  New: Nov. 20, 3:18 p.m.

Space Highlights

Nov. 9, 1934 ~ Birthday of astronomer, exobiologist, adventurer, writer, promoter and TV personality Carl Sagan. He died in 1996.

Nov. 20, 1889 ~ Birthday of American astronomer Edwin Hubble. The Hubble space telescope is named in his honor.

Nov. 26, 1965 ~ The first French satellite was launched.

Nov. 29, 1967 ~ The first Australian satellite was launched.

Nov. 30, 1954 ~ Ann Hodges was napping in her Alabama home when a 3-pound meteorite crashed through the house and hit her after bouncing off some furniture. She suffered a bruise on the hip. (Don’t let this event deter you from watching meteor showers.)

Dec. 14, 1972 ~ Apollo 17 astronaut Gene Cernan became the last human to stand on the moon.

If you've picked up this copy of Inside/Outside - and managed to find this column - in the first week of November, you should take note of a relatively rare astronomical event that occurs on Wednesday, Nov. 8 - and it won't involve hanging out in the chill of the night.

The innermost planet, Mercury (yes, unlike forlorn Pluto, it's still a planet), passes in front of (transits) the sun. On average, a Mercury transit occurs once in seven years, 14 times in this century. The last one, in 2003, was not visible in our part of the world. If you miss the Nov. 8 event, you'll have another chance in 2016.

From our vantage point, only the inner planets, Mercury and Venus, transit the sun. Venus transits are much less frequent that those of Mercury, although the next one of those is in 2012.

Unfortunately, a transit is not something you can easily view. Mercury is too small and the sun too bright to watch without eye protection and a telescope. A good, small scope with a high-quality solar filter - in front of the optics - should do the trick. Since Mercury's disk is only about half of 1 percent the apparent diameter of the sun, you will need a magnification of at least 50 times to spot it.

According to my planetarium program, Mercury will touch the sun's rim at 12 minutes past noon Mountain Time. The transit will last about five hours. Mercury will exit the solar disk around sunset. Folks in Utah, Arizona and farther west may see the transit's end very near the western horizon. Coloradans will miss the final moments.

Remember: Never look at the sun without proper eye protection!

Following its rendezvous with the sun, you can spot Mercury low in the east in the predawn sky in mid- to late November. It reaches its greatest western elongation (apparent distance from the sun) on the 25th.

Jupiter and Mars join Mercury before sunrise in early December. Look for them clustered within 3 degrees beginning on the 8th. On the 10th, Jupiter and Mercury will be within half a degree, and much fainter Mars will be about a degree to the southeast of the pair. With the sun not far below the horizon, you may need binoculars to spot the trio in the brightening sky.

Rising much earlier, Saturn, in the constellation Leo, graces the late evening sky. Look for it after midnight high in the south. The bright star nearby is Regulus.

Brilliant Venus remains hidden in the sun's glare until the second week of December when it returns to the early evening sky. Look for it very low in the southwest right after sunset.

A couple of meteor showers hold promise. The Leonid shower peaks on the morning of Nov. 18. It typically yields around 10 per hour, although there is the occasional "storm." It's worth a good look. The nearly new moon won't rise until about 5 a.m., so viewing should be ideal. The more reliable and productive Geminid shower peaks on the morning of Dec. 14. It often produces 60 to 120 "shooting stars" per hour. Begin your serious viewing around midnight. The waning crescent moon rises around 1:40 a.m. Face away from it and continue looking.

During the early evening of Dec. 3, the nearly full moon passes in front of the Pleiades star cluster, occulting several stars. The moon's glare will make it difficult to observe, however.

Christmas is almost at hand. Did you remember to put that new eyepiece, filter or digital imager on your wish list? Don't forget: Stargazers always appreciate warm clothes, insulated boots, gloves and hats too. Those all-nighters get mighty cold this time of year.

Lewis McCool writes from his home near Dolores, Colo., where he can take advantage of clear nights and dark skies.