The sky, June 17-23; Happy Solstice on the 20th

Special to, June 17, 2024

Excerpts from weekly Sky&Telescope report.


■ Have you ever knowingly seen even a bit of the constellation Centaurus? Famous Alpha Centauri never gets above the horizon unless you’re as far south as San Antonio or Orlando (latitude 29° N). But fairly easy from much farther north is Theta Centauri, magnitude 2.0.

This evening the Moon makes it simple to find. Right after nightfall, look 19° (nearly two fists) straight down from the Moon. No other star in that area is quite as bright. Theta Cen is pale orange, as binoculars will confirm. It’s at declination –36.5°, hardly farther south than the bottom of the Sagittarius Teapot. It’s even 1° less far south than the familiar Cat’s Eyes in the tail of Scorpius.

Theta Cen marks the top of the stick-figure Centaur’s head. Add another constellation to your life list, at least of those where you’ve identified some fragment.


■ After nightfall is complete, Vega is the brightest star very high in the east. Barely lower left of it is 4th-magnitude Epsilon Lyrae, the Double-Double. Epsilon forms one corner of a roughly equilateral triangle with Vega and Zeta Lyrae. The triangle is less than 2° on a side, hardly the width of your thumb at arm’s length.

Binoculars easily resolve Epsilon. And a 4-inch telescope at 100× or more should resolve each of Epsilon’s wide components into a tight pair.

Zeta Lyrae is also a double star for binoculars; much tougher, but plainly resolved in a telescope.

Delta Lyrae, below Zeta, is a much wider and easier pair, reddish orange and pale blue.


■ The waxing gibbous Moon tonight shines among the stars of upper Scorpius as shown below. Orange Antares is about 3° or 4° to the Moon’s left or lower left, and Delta Scorpii, the next brightest star in the area, is a somewhat similar distance above the Moon or to its upper right. Delta is the middle star of the upper row of three in the graphic. Cover the bright Moon with your finger to get a better look at the stars around it.

Moon crossing Scorpius, June 18-20, 2024

The nearly full Moon Wednesday night hangs with Antares and Delta Scorpii, among other stars of upper Scorpius. Delta Sco, a long-term variable, is currently much the brightest of the row of three stars above the Moon that marks Scorpius’s head. (Its brightness on this map is decades old.)


■ Happy solstice! At 4:45 p.m. EDT this afternoon, the Sun reaches its farthest north position in Earth’s sky and begins its six-month return southward. Astronomical summer begins in the Northern Hemisphere, winter in the Southern Hemisphere.

For us northerners, this is the year’s longest day and shortest night.

It’s also the day when (in the north temperate latitudes) the midday Sun passes the closest it ever can to being straight overhead, and thus when your shadow becomes the shortest it can ever be at your location. This happens at your local apparent [solar] noon, which is probably rather far removed from noon in your civil (clock) time.

And if you have a good west-northwest horizon (in mid-northern latitudes), mark carefully where the Sun sets. In a few days you should be able to detect that the Sun is once again starting to set a just little south (left) of that point.


■ Full Moon (exactly full at 9:09 p.m. EDT). After dark, cover the Moon with your finger to get a better look at the stars around it. You’ll see that the Moon sits barely above the spout of the Sagittarius Teapot.

Jupiter is getting a little higher in bright dawn every morning. Even so, bring binoculars.


■ Now the Moon shines barely below the Teapot’s handle through the evening hours.


■ Leo the Lion is mostly a constellation of late winter and spring. But he’s not gone yet. As twilight ends look due west, somewhat low, for Regulus, his brightest and now lowest star: the forefoot of the lion stick figure.

The Sickle of Leo extends upper right from Regulus. The rest of the Lion’s constellation figure runs for almost three fist-widths to the upper left from the Sickle, to his tail tip Denebola, the highest of his stick-figure’s stars. Leo will soon be treading offstage into the sunset.

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