Evan Hazard: A planetary dance after sundown
Last month I suggested that you could find all April’s minima of Algol at www. nightskyinfo.com/sky _highlights/ algol/ – "a site giving the minima in 24-hour mode, where 1911 = 7 p.m., and in UT (Greenwich Standard Time). Subtract 5 hours to get CDT." That 1911 should be 1900. I also told you Jupiter was our only bright evening planet, and then noted that Saturn was at its brightest, rising in the east as Sol set in the west. None of this was the paper’s fault. Mea culpa.
From only two evening planets in April, we come to four in May. Mars is hiding behind Sol’s glare all month. Saturn is still pretty much at its brightest, rising at dusk in the east and remaining visible all night. Most of the action, however, is in the west. After sundown, we’ll be looking past Sol across the solar system toward distant Jupiter with Venus and Mercury coming around from behind Sol toward us. Jupiter’s rapid descent toward Sol will mostly result from our more rapid movement in our orbit. But Venus, now our Abendstern, and Mercury move faster than Earth, causing their rapid apparent motion up from the horizon.
Jupiter is still prominent in the west at sundown. By month’s end, however, it will set less than an hour after Sol, but will have company. On Mayday, Venus, now our Abendstern, will be just above the WNW horizon, and Jupiter will be 27 degrees above and to the left. Venus is catching up with us but will move only slightly above the horizon through the month. Jupiter’s apparent rapid movement will bring their separation down to one degree on May 28. Meanwhile, Mercury, racing along back of Sol now, will show up.
Thirty minutes after sunset May 19, a line extended from Jupiter past Venus will lead to Mercury just above the horizon. Best use binocs to see it in the glare. By May 24-29, the three planets will form a triangle, changing shape from night to night, as Jupiter nears the sunset and Venus and Mercury rise. Eventually it’s a line again, with Jupiter closest to the horizon. Jupiter will reappear in the pre-dawn sky in June.
Did anyone get to see Comet STARRS? I didn’t, but I’ve seen Hale-Bopp, Halley and a few I read about that were only visible in telescopes. Can’t complain.
Summer constellations are coming up in the east, unconcerned about our April snow cover. Hercules is high in the east; binocs will reveal M13, the famous globular cluster on the west edge of its central "keystone." By the end of May, consider DEET before stargazing.
This column is dedicated to the memory of the girl I married 61 years ago today.
EVAN HAZARD also writes "Threescore and Ten" for The Pioneer’s "Prime Time."