FRIDAY, JUNE 24
■ After dark, look southeast for orange Antares, "the Betelgeuse of summer." (Both are 1st-magnitude "red" supergiants). Around and upper right of Antares the other, whiter stars of upper Scorpius form their distinctive pattern. The rest of the Scorpion curls down toward the horizon.
Also right after dark, spot Arcturus way up high toward the southwest. Three fists below it is Spica. A fist and a half to Spica's lower right, four-star Corvus, the Crow of spring, is sliding down and away.
■ In the early dawn of Saturday June 25th, the waning crescent Moon forms a diagonal line with Venus and low Mercury, as shown below. Mars, Jupiter, and Saturn are spread in a long line far to the upper right of this gathering .
SATURDAY, JUNE 25
■ This is the time of year when the two brightest stars of summer, Arcturus and Vega, are about equally high overhead soon after dark: Arcturus toward the southwest, Vega toward the east.
Arcturus and Vega are 37 and 25 light-years away, respectively. They represent the two commonest types of naked-eye star: a yellow-orange K giant and a white A main-sequence star. They're 150 and 50 times brighter than the Sun, respectively — which, combined with their nearness, is why they dominate the evening sky.
■ Low in the dawn of Sunday the 26th, the waning crescent pairs with Venus, as shown above.
SUNDAY, JUNE 26
■ Low in the northwest or north at the end of these long summer twilights, would you recognize noctilucent clouds if you saw them? They're the most astronomical of all cloud types, what with their extreme altitude and their formation (in part) on meteoric dust particles. They used to be fairly rare, but they've become more common in recent years as Earth's atmosphere changes. See Bob King's Nights of Noctilucent Clouds.
■ Very low in the brightening dawn Monday the 27th, the thin crescent Moon hangs left of Mercury as shown above. Binoculars will help.
MONDAY, JUNE 27
■ Today's sunset is the latest of the year (if you live near latitude 40° north), even though the solstice was on the 21st. This slight discrepancy, amounting to only a minute or so, arises from the tilt of Earth's axis and the ellipticity of Earth's orbit — like the somewhat larger winter equivalent in December, which moves the earliest sunset from the solstice to about December 7th.
TUESDAY, JUNE 28
■ Look for the Big Dipper hanging straight down in the northwest as soon as darkness is complete. Its bottom two stars, the Pointers, point toward modest Polaris to their lower right, by about three fists at arm's length.
Polaris is the end of the Little Dipper's handle. From there the rest of the Little Dipper floats upward. Perhaps it's a helium balloon escaped from some June evening party, trailing its string. Through light pollution, however, all you may see of the Little Dipper are Polaris at its bottom and Kochab, the lip of the Little Dipper's bowl, at the top. The rest of its stars are pretty dim at 3rd to 5th magnitude.
■ New Moon (exact at 10:52 p.m. EDT).
WEDNESDAY JUNE 29
■ Arcturus and Vega are about equally far from straight overhead shortly after dark: Arcturus toward the southwest, Vega toward the east.
Arcturus is pale yellow-orange; Vega is icy bluish white. Star colors are mostly subtle, and different people have an easier or harder time seeing them. To me, the tints of bright stars show a little better in the dark blue of a late-twilight sky than in a fully dark sky.
For instance, compare Vega and Arcturus in twilight and after dark. Do their colors stand out a little better or worse for you one way or the other?
Binoculars, of course, always make star colors much more obvious.
THURSDAY, JUNE 30
■ Leo the Lion is mostly a constellation of late winter and spring evenings. 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 two or three fist-widths to the upper left from there, to his tail star Denebola, the highest. He'll soon be treading offstage into the sunset.
FRIDAY, JULY 1
■ On the eastern side of the sky, the Summer Triangle holds sway after dark. Its top star is Vega, the brightest on that entire half of the sky. The brightest star to Vega's lower left is Deneb. Farther to Vega's lower right is Altair, with fainter Tarazed just above it. The Milky Way (if you have deep darkness) runs across the Triangle just inside its bottom edge.
As evening grows late and even Altair rises high, look left or lower left of it, by hardly more than a fist, for the compact little constellation Delphinus, the Dolphin.
Did you get it? Then try for even fainter, smaller Sagitta, the Arrow. It's to Altair's upper left, just a little closer. The Arrow points lower left, past the head of Delphinus.
SATURDAY, JULY 2
■ In twilight this evening, look west for the waxing crescent Moon. Look left of the Moon for Regulus and above the Moon for slightly fainter Algieba, Gamma Leonis, as shown below. Binoculars help reveal the color difference between the two stars. Algieba is a wide optical double for binoculars and a much closer true binary (5 arcseconds) for telescopes.
This Week's Planet Roundup
Seven dawn planets! All five naked-eye planets remain lined up in the dawn, in good view for most of this week. From Mercury through Saturn, they run from low in the east-northeast to high in the south as dawn brightens.
By coincidence, they happen to be arranged in order of their distance from the Sun, counting from lower left to upper right. Dim, sub-naked-eye Uranus and Neptune also lurk among them.
Mercury is low in the glow of sunrise, glimmering 10° to 13° lower left of bright Venus this week. See the scene at the top of this page. Mercury sinks a little lower into the sunrise day by day, even as it brightens from magnitude –0.2 to –0.8. Binoculars help.
Fainter Aldebaran, magnitude +0.8, sparkles weakly in Mercury's vicinity.
Venus (magnitude –3.9) rises just as dawn begins. Look for it above the east-northeast horizon. It's very far lower left of bright Jupiter, by roughly six fists at arm's length.
Mars and Jupiter, very different at magnitudes +0.5 and –2.4 respectively, shine in the east-southeast before and during early dawn, near the Pisces-Cetus border. Mars glows to Jupiter's lower left. They continue to move apart, separating from 16° to 20° this week.
Saturn, magnitude +0.7, rises around 11 p.m. in eastern Capricornus. By the beginning of dawn you'll find it in the south. It's some 40° (about four fists) to the right of Jupiter.
The little star less than 2° to Saturn's lower right is Delta Capricorni, magnitude 2.8. Saturn has stayed near Delta Cap for weeks, because the planet is near its stationary point: the eastern end of the retrograde loop on the sky that it performs every 12½ months. Delta Cap will keep fairly close company with Saturn all the way through August.
Uranus, magnitude 5.8 in Aries, is low in the east before the first light of dawn, between Venus and Mars.
Neptune, magnitude 7.9 at the Aquarius-Pisces border, is high in the southeast before the first light of dawn, between Jupiter and Saturn.
All descriptions that relate to your horizon — including the words up, down, right, and left — are written for the world's mid-northern latitudes. Descriptions and graphics that also depend on longitude (mainly Moon positions) are for North America.
Eastern Daylight Time, EDT, is Universal Time minus 4 hours. (Universal Time is also called UT, UTC, GMT or Z time.)
Want to become a better astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.
This is an outdoor nature hobby. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential magazine of astronomy.
Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The basic standard is the Pocket Sky Atlas (in either the original or Jumbo Edition), which shows stars to magnitude 7.6.
Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; nearly three times as many. The next up, once you know your way around, are the even larger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to magnitude 9.75). And be sure to read How to Use a Star Chart with a Telescope. It applies just as much to charts on your phone or tablet as to charts on paper.
You'll also want a good deep-sky guidebook. A beloved old classic is the three-volume Burnham's Celestial Handbook. An impressive more modern one is the big Night Sky Observer's Guide set (2+ volumes) by Kepple and Sanner.
Can a computerized telescope replace charts? Not for beginners, I don't think, and not on mounts and tripods that are less than top-quality mechanically, meaning heavy and expensive. And as Terence Dickinson and Alan Dyer say in their Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."
Audio sky tour. Out under the evening sky with your
earbuds in place, listen to Kelly Beatty's monthly
podcast tour of the heavens above. It's free.
"The dangers of not thinking clearly are much greater now than ever before. It's not that there's something new in our way of thinking, it's that credulous and confused thinking can be much more lethal in ways it was never before."
— Carl Sagan, 1996
"Facts are stubborn things."
— John Adams, 1770