This Week’s Sky at a Glance, September 4 – 12 – Sky & Telescope


■ Jupiter and Saturn, shining within the south, flip horizontal in twilight. Every night they get this manner a couple of minutes earlier. The pair tilts to the suitable as night advances.

■ The waning gibbous Moon rises across the finish of twilight this night. Once it is up, look ahead to fiery Mars, now unusually brilliant at magnitude –2.0, to rise about a fist-width or a little extra (13°) to the Moon’s decrease left. Mars will come up about 30 or 40 minutes after the Moon if you happen to reside within the mid-latitudes of North America.Over the Moon is the Great Square of Pegasus, balanced on one nook. The complete scene climbs increased as night grows late.

The waning gibbous Moon passes brilliant Mars. But no, the Moon will not occult Mars for many of us on Saturday the fifth! The Moon right here is at all times drawn about thrice its precise obvious dimension, so that they’ll miss (until you are in elements of South America or, after dawn, northern Africa or southernmost Europe. (Map and particulars in case that is you: Seen from the center of North America at 11 p.m., Mars shall be standing off about one Moon diameter (½°) from the Moon’s northern limb. SATURDAY, SEPTEMBER 5

■ The Moon and Mars rise shut collectively within the east about a half hour after the top of twilight. For skywatchers in North America they will be solely about 1° aside or much less. By daybreak Sunday, they will stand excessive within the southwest 2° or 3° aside.

■ Jupiter’s Great Red Spot ought to transit Jupiter’s central meridian round 10:18 p.m. Eastern Daylight Time. It needs to be seen for about an hour earlier than and after in a good 4-inch telescope if the atmospheric seeing is sharp and regular. A light-weight blue or inexperienced filter helps.

The Red Spot transits about each 9 hours 56 minutes. But not fairly like clockwork! It drifts east or west in Jupiter’s ambiance considerably irregularly. A modifications usually turns into detectable to visible transit timers over a span of a number of months. Our transit-time predictions are based mostly on pretty latest observations, however do not be shocked if the Red Spot has taken it into its head to float a couple of minutes off schedule.


■ This night we get about an hour of fine darkness between the top of twilight and the rising of the Moon. Use it to get out your binoculars and discover the small Milky Way star cloud generally known as M24, in Sagittarius north of the Teapot. It’s roughly 1° large. What you are really trying into right here is a “tunnel in space,” as Matt Wedel notes in his September Binocular Highlight (September Sky & Telescope, web page 43, with chart). Interstellar mud clouds usually block our view deep into the Milky Way’s aircraft. But “M24” is a fortunate lineup of gaps within the clouds for some 10,000 to 16,000 mild-years, roughly midway to the Milky Way’s central area. No surprise the celebs listed below are so wealthy!


■ A winter preview: Step out earlier than the primary mild of daybreak this week, and the sky, (with a waning Moon) shows the identical starry panorama it does at dinnertime round New Year’s. Orion is striding up within the southeast, with Aldebaran and the Pleiades excessive above it. Sirius sparkles far down beneath Orion. The Gemini twins are mendacity on their sides effectively up within the east.


■ Most variable stars for novice telescopes take days to weeks to vary brightness noticeably. But the quickest eclipsing binary stars can change visibly inside 10 minutes. A number of such quick eclipsers, with finder charts, await you and your scope in Bob King’s new article Take a Roller Coaster Ride on a Fast Eclipsing Binary.Years in the past, I might spend hours by means of a quiet night time fastidiously noting the altering magnitude of some such faint star for the AAVSO’s Eclipsing Binary Section. I used to be utilizing a do-it-yourself 6-inch reflector on my dad and mom’ garden with simply my eye and an AAVSO comparability-star chart, having deliberate issues out with a checklist of eclipse predictions. The objective was, and is, to trace any slight drifts within the instances of mid-eclipse from the anticipated instances, indicating tiny modifications within the stars’ orbital interval throughout months or years. Such modifications can reveal mass exchanges, both regular or sudden; the affect of an unseen, third orbiting companion; modifications intrinsic to one of many stars, or different results.Nowadays amateurs do that with better precision and reliability utilizing digital imaging. But for me, that visible program was actually what turned me into a severe novice astronomer.

This week, Saturn and Jupiter are almost horizontal as the celebs come out.WEDNESDAY, SEPTEMBER 9

■ The final-quarter Moon rises round 11 tonight daylight-saving time, relying in your location. The Pleiades are lower than a fist at arm’s size above it, and, as soon as the Moon is a little increased, you may spot orange Aldebaran beneath it or to its decrease left.

The Moon is strictly final-quarter at 5:26 a.m. Thursday morning EDT. By daybreak Thursday it is very excessive within the south, nonetheless between Aldebaran and the Pleiades. Lower left of them stands Orion.


■ The large W sample of Cassiopeia is tilting up within the northeast these nights. Look beneath the W’s final section, the one on the decrease left, by a little farther than the section’s size. Can you see an enhanced little spot of the Milky Way’s glow right here? Binoculars will present it to be the Perseus Double Cluster — even by means of a honest quantity of sunshine air pollution.

■ Jupiter’s Great Red Spot ought to transit round 9:27 p.m. Eastern Daylight Time.


■ Vega now passes the zenith an hour after sundown throughout late twilight, for these of us at mid-northern latitudes. Vega is larger, hotter, and 50 instances brighter than our Sun. But at a distance of 25 mild-years, it is 1.6 million instances farther away. The Sun is simply 8.Three mild-minutes from us.


■ By 9 or 10 p.m. two of the perfect-recognized deep-sky objects, the Double Cluster in Perseus (see Thursday above) and the Great Andromeda Galaxy M31, are in excessive view within the east. Did you already know they’re solely 22° aside? They’re each cataloged as 4th magnitude however to the bare eye they give the impression of being quite totally different, the extra so the darker your sky. See for your self; they’re plotted on the all-sky constellation map within the heart of the September Sky & Telescope, which needs to be all of the map it’s worthwhile to determine their places. They’re beneath Cassiopeia and farther to Cassiopeia’s proper, respectively. Sky too brilliant? Use binoculars!

The two clusters of the Double Cluster (NGC 869 and NGC 884) are at very related distances about 7,600 mild-years away. M31, at 2.5 million mild-years, is about 330 instances farther.


This Week’s Planet Roundup

Mercury is buried deep within the sundown.

Venus (magnitude –4.2, in dim Cancer) rises in deep darkness two hours earlier than daybreak begins, a bizarre UFO within the east-northeast beneath Castor and Pollux. By the time daybreak will get underneath manner, Venus shines pretty excessive within the east.In a telescope Venus continues to shrink (it is now about 19 arcseconds in diameter) whereas changing into extra gibbous (61% sunlit).

Mars is massive, brilliant and shut because it nears its October 13th opposition. This week it rises brilliant orange — shining at magnitude –2.0! — within the east quickly after the top of twilight. It climbs increased by means of the night and stands at its highest and telescopic finest round Three or 4 a.m. daylight-saving time, lording over the world from excessive within the south. This week Mars grows from 19 to 20 arcseconds in obvious diameter, almost as massive as will probably be when passing closest by Earth a month from now.

Mars remains to be noticeably gibbous, 94% sunlit. Look for its white South Polar cap, doable clouds particularly close to the limb, and dusky floor markings. To get a map of the aspect dealing with Earth at the date and time you may observe, you need to use our Mars Profiler. The map there may be sq.; bear in mind to mentally wrap it onto the aspect of a globe. (Features close to the map’s edges grow to be very foreshortened.)

Mars on August 27th, imaged at very excessive decision by Enrico Enzmann and Damian Peach with a 76cm (30-inch) telescope. South is up. Dark Syrtis Major juts down from heart. Upper left of it’s darkish Mare Tyrrhenum. Above them is the big, round Hellas Basin, lighter in colour however not as brilliant as when it is stuffed with cloud or frost. Sinus Meridiani is at the middle of the suitable-hand (morning) limb.The South Polar Cap continues to shrink, and simply off its edge, solely a little stays of Novus Mons. In a picture Enzmann and Peach took simply six days earlier, the Novus Mons patch was sharply outlined and starkly white.Jupiter and Saturn (magnitudes –2.5 and +0.3, respectively) shine within the south in early night. Jupiter is the brightest. Saturn stays 8° to its left.They flip completely horizontal throughout twilight. Lower proper of Jupiter after darkish is the deal with of the Sagittarius Teapot. The brightest star of the Teapot’s deal with (the highest one) is Sigma Sagittarii or Nunki, magnitude 2.0. It’s a sizzling blue-white star, 4.5 instances the Sun’s diameter, 3300 instances as luminous, and 230 mild-years away. Follow the telescopic interaction of Jupiter with its moons and their shadows, and discover all of the transit instances of Jupiter’s Great Red Spot, within the Celestial Calendar part of the September Sky & Telescope, web page 50.

Jupiter on August 23rd, imaged by Christopher Go at 11:28 UT. South right here is up. Note the darkish “eyeliner” that now outlines the north aspect of the Red Spot Hollow. Broad, bluish festoon bases line the south fringe of the reddish, chaotic North Equatorial Belt. And discover the “white whale” of an upwelling outbreak within the slender North Tropical Zone. Another aspect of Jupiter, imaged by Go on September 2nd at 12:07 UT underneath poorer situations. On this aspect too, a new outbreak simply has appeared within the North Tropical Zone. Writes Go on September 2nd, “This storm was discovered by Eric Sussenbach 10 hours ago! Congratulations Eric for this discovery!” Uranus (magnitude 5.8, in Aries) is effectively up within the east by midnight daylight-saving time, east of Mars.

Neptune (magnitude 7.8, in Aquarius) is increased within the south-southeast by that point. Finder charts for Uranus and Neptune.

All descriptions that relate to your horizon — together with the phrases up, down, proper, and left — are written for the world’s mid-northern latitudes. Descriptions that additionally rely on longitude (primarily Moon positions) are for North America.

Eastern Daylight Time, EDT, is Universal Time (also referred to as UT, UTC, GMT, or Z time) minus 4 hours.

Want to grow to be a higher astronomer? Learn your manner across the constellations. They’re the important thing to finding all the pieces fainter and deeper to hunt with binoculars or a telescope.

This is an out of doors nature pastime. For a simple-to-use constellation information protecting the entire night sky, use the large month-to-month map within the heart of every situation of Sky & Telescope, the important journal of astronomy.

Once you get a telescope, to place it to good use you may want a detailed, giant-scale sky atlas (set of charts). The fundamental normal is the Pocket Sky Atlas (in both the unique or Jumbo Edition), which reveals stars to magnitude 7.6.

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and a whole bunch of telescopic galaxies, star clusters, and nebulae amongst them. Shown right here is the Jumbo Edition, in onerous covers and enlarged for simpler studying outdoor at night time. Sample chart. More in regards to the latest new editions.Next up is the bigger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; almost thrice as many. The subsequent up, as soon as you already know your manner round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to magnitude 9.75). And learn methods to use sky charts with a telescope.

You’ll additionally need a good deep-sky guidebook, corresponding to Sky Atlas 2000.0 Companion by Strong and Sinnott, or the larger (and illustrated) Night Sky Observer’s Guide by Kepple and Sanner.

Can a computerized telescope change charts? Not for newcomers, I do not assume, and never on mounts and tripods which are lower than prime-high quality mechanically, which means heavy and costly. And as Terence Dickinson and Alan Dyer say of 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 underneath the night sky with yourearbuds in place, hearken to Kelly Beatty’s monthlypodcast 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

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