By Mike Lynch
The biggest astronomical event by far this month, if not this year, is coming late Tuesday afternoon and evening. It is the transit of Venus, when the second closest planet to our sun passes directly in front of the sun.
The such transit happened in 2004 and won’t happen again until 2117.
Since December Venus has been dazzling our evening sky like a super bright beacon, but later this month we’ll begin seeing it in the early morning sky. A little after 3 p.m. on Tuesday afternoon the silhouette of the 7,500-mile-wide planet, which is now only about 21 million miles from Earth, will begin its transit on the upper right limb of the sun’s disk and will work its way down the right side.
Unfortunately Venus will only be about halfway across the sun when the sun sets shortly after 8:30 p.m.
It’s absolutely dangerous to try to watch this directly unless you have special solar glasses or a solar filter for your telescope. Actually the best way to see it is on the Web (www.exploratorium.edu/venus/).
The transition to summer skies is just about complete. The stars and constellations of winter are pretty much gone from our evening skies, all setting well before the sun. The only bright winter stars left are Castor and Pollux in the constellation Gemini the Twins. Toward the end of evening twilight you can see them side-by-side in the very low northwestern sky.
The planets Saturn and Mars are lighting up the southwest quarter of the celestial dome after evening twilight, with Saturn definitely the better telescope target.
If you lie back on that reclining lawn chair and look straight overhead toward the zenith you’ll easily see the Big Dipper, and not far from the Dipper’s handle you’ll see a bright orange star. That’s Arcturus, the second brightest star in the sky, which is about 36 light-years or 208 trillion miles away.
The light that we see tonight from Arcturus, almost 70 times the diameter of our sun, left that star when Nixon was president. Arcturus is also the brightest star in the constellation Bootes the Hunting Farmer, which actually looks more like a giant nocturnal kite with Arcturus at the tail of the kite.
Sky map instructions
To use this map, cut it out and attach it to a stiff backing. Hold it over your head and line up the compass points on the map’s horizon to the actual direction you’re facing. East and West on this map are not backward. When you hold this map over your head, East and West will be in their proper positions. Attach a piece of red cloth or paper over the lens of a small flashlight so you don’t lose your night vision when you look at this map in red light.