FRIDAY, AUGUST 26
■ Late these evenings as autumn approaches, Fomalhaut, the Autumn Star, makes its inevitable appearance above the southeast horizon. Its rising time will depend on where you live. But by 10 or 11 p.m. you should have no trouble identifying it sparkling low in the southeast if you have a good view in that direction. No other 1st-magnitude star is anywhere near there.
Hint: It's about two fists lower left of Saturn.
SATURDAY, AUGUST 27
■ Another sign of the advancing season: Cassiopeia is high in the northeast, its W pattern tilting up. And below it, starry Perseus is reaching up.
The highest part of Perseus includes the wintry Double Cluster. To find it, look below the lowest two stars of the Cassiopeia W, by 1½ times the distance between them. You're looking for what seems like a small spot of enhanced Milky Way glow. Binoculars or a finderscope will help you detect the Double Cluster even through a fair amount of light pollution. In a telescope the pair are a glory: a distant twin city of stars.
■ The asteroid 4 Vesta is just past opposition and showing itself at a relatively bright magnitude 6.2 this week. It's in western Aquarius about 8° southeast of 3rd-magnitude Delta Capricorni, Saturn's near neighbor. Use binoculars or a telescope with the finder chart in the August Sky & Telescope, page 49 (or the less detailed chart at Observe Vesta — and own a piece of it, too.)
■ New Moon (exact at 4:17 a.m. on this date EDT).
SUNDAY, AUGUST 28
■ The Sagittarius Teapot is still nearly on the meridian (due south) right after nightfall is complete. It's tilting to pour to the right. Explore with binoculars before moonlight returns later this week.
MONDAY, AUGUST 29
■ Soon after sunset, like 20 minutes or so, start scanning for the super-thin crescent Moon quite low over the west horizon in bright twilight. Binoculars or a wide-field telescope may make the difference for spotting it if the air is not crystal clear.
Got the Moon? Then look about 6° below it for little Mercury heading down and away.
TUESDAY, AUGUST 30
■ As twilight fades look low in the west for the crescent Moon, less thin and delicate than yesterday, with little Spica 4° or 5° to its left.
Some three fists to their upper right, Arcturus glimmers through the twilight.
WEDNESDAY, AUGUST 31
■ Now the thickening Moon hangs upper left of Spica in the western twilight, by roughly a fist at arm's length.
THURSDAY, SEPTEMBER 1
■ The change of August to September means that Scorpius, which was the proud starring constellation of the south during the height of summer, now turns to lie horizontally in the southwest after nightfall is complete, preparing to bed down for the season.
The Moon, getting near first quarter, hangs to Scorpius's right.
FRIDAY, SEPTEMBER 2
■ Now the Moon, nearly first quarter, poses just to the right of the head of Scorpius after dusk as shown below. The star closest to the Moon there is Delta Scorpii, the brightest in the area after Antares.
■ How soon after sunset can you see the big Summer Triangle? Face east and look way up. Vega, the Triangle's brightest star, is nearly at the zenith (for skywatchers at mid-northern latitudes). Deneb is the brightest a couple fists to Vega's east-northeast. Altair shines less high in the southeast, farther from Vega.
■ A winter preview: Step out before the first light of dawn this week, and the sky displays the same starry panorama it does at dinnertime around New Year's. Orion is striding up in the southeast, with Aldebaran and then the Pleiades high above it. Sirius sparkles far down below Orion. The Gemini twins are lying on their sides well up in the east, left of Orion.
And brilliant Mars, currently dominating the scene near Aldebaran as shown below, is no planetary anachronism in this preview. The doings of its retrograde loop in the next four months will keep it in the general vicinity of Aldebaran — and make it even brighter than it is now.
SATURDAY, SEPTEMBER 3
■ First-quarter Moon (exact at 2:08 p.m. EDT). Nightfall in North America finds the Moon in the south-southwest a few degrees upper left of Antares, as shown above. The next-brightest star there is Delta Scorpii, 8° to the right of Antares.
■ Mars is just 4½° above Aldebaran in the dawn Sunday morning the 4th as shown below. This is essentially as close as they'll get; Mars passes widely north of Aldebaran this coming week.
This Week's Planet Roundup
Mercury is fading and sinking very low into the sunset glow. Early in the week, you can try scanning for it with binoculars or a wide-field telescope about 20 or 30 minutes after sunset. Look just above the horizon a little left of due west. Good luck.
Don't be misled if you sweep up sparkly Spica. It's some 20° to Mercury's upper left.
A super-thin crescent Moon hangs about 6° above Mercury in the twilight of August 29th.
Venus, magnitude –3.9 in Leo, rises about a half hour after dawn begins. As dawn brightens, look for it very low in the east.
Mars, magnitude –0.1 in Taurus, rises around 11 or midnight in the east-northeast. By early dawn it shines very high in the southeast. Mars is now three times as bright as similarly colored Aldebaran, magnitude +0.9, a little way below it.
Mars is 10 arcseconds in apparent diameter and growing. It'll be 17.2 arcseconds wide when closest to Earth on December 1st.
Jupiter rises due east in twilight. By dark it's glaring low at a bright magnitude –2.8. Jupiter stands highest in the south around 2 or 3 a.m. daylight-saving time, in an undistinguished area near the Pisces-Cetus border.
In a telescope Jupiter is 49 arcseconds wide, nearly its maximum possible! Even though it doesn't reach opposition until September 26th. That's because this year it's nearly at the perihelion of its 12-year orbit around the Sun.
Saturn, magnitude +0.3 in western Capricornus, was at opposition August 14th. Now you can spot it in the southeast in late twilight. It's higher later in the evening and at its highest and best in the south around 11 or midnight. It sets around the beginning of dawn.
Saturn's rings appear roughly as wide, end to end, as Jupiter's globe. See the August Sky & Telescope, page 48.
Uranus, magnitude 5.7 in Aries, is west of Mars before dawn.
Neptune, magnitude 7.8 at the Aquarius-Pisces border, rises in evening twilight west of Jupiter.
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