Friday, October 26
• The waning gibbous Moon is well up in the east by late evening, with the Pleiades above it and Aldebaran closer to its lower left as shown here (for North America).
• The Ghost of Summer Suns. Halloween is approaching, and this means that Arcturus, the star sparkling low in the west-northwest in twilight, has taken on its role as "the Ghost of Summer Suns." What does that mean? For several days around October 25th every year, Arcturus occupies a special place above your local landscape. It closely marks the spot where the Sun stood at the same time, by the clock, during hot June and July — in broad daylight, of course! So, as Halloween approaches every year, you can see Arcturus as the forlorn, chilly ghost of the departed summer Sun.
Saturday, October 27
• A small telescope will show Saturn's largest moon, Titan, about four ring-lengths to Saturn's west this evening.
• The dog-bone-shaped asteroid 216 Kleopatra, with its two tiny moons, should occult an 11th-magnitude star in Canis Minor during Sunday's early-morning hours along a path from central Alberta through upstate New York and Long Island. Details, map, finder charts.
Sunday, October 28
• This is the time of year when the dim Little Dipper extends straight left from Polaris right after dark. If your sky is light polluted, the only stars of it you'll see are Polaris (its handle-end) and the end of its bowl: Kochab and Pherkad, the "Guardians of the Pole." They're left of Polaris by about a fist and a half at arm's length.
Check again around 2 a.m., and they'll be straight below Polaris.
Monday, October 29
• Draw a line from Altair, the brightest star very high in the southwest after dark, to the right through Vega, very high in the west and even brighter. Continue the line half as far onward and you hit the Lozenge: the pointy-nosed head of Draco, the Dragon.
Its brightest star is orange Eltanin, the tip of the Dragon's nose, always pointing toward Vega.
Tuesday, October 30
• Spot bright Altair high in the southwest soon after dark. Two distinctive little constellations lurk above it: Delphinus the Dolphin, hardly more than a fist at arm's length to Altair's upper left, and fainter Sagitta the Arrow, slightly less far to Altair's upper right. Sky too bright? Use binoculars!
Wednesday, October 31
• This Halloween the evening is moonless. In early evening, the two brightest celestial objects in good view are Vega high in the west and Mars lower in the south.
Draw a line between them. A little below the line's midpoint shines Altair, with fainter Tarazed to its upper right by about a finger width at arm's length.
• Last-quarter Moon (exactly so at 12:40 p.m. EDT). The Moon, between Cancer and Leo, rises around midnight or 1 a.m. depending on your location, in the east-northeast far below Castor and Pollux.
Thursday, November 1
• Vega is the brightest star very high in the west on November evenings. Its little constellation Lyra extends to its left, pointing in the direction of Altair, the brightest star in the southwest.
Three of Lyra's leading stars, after Vega, are interesting doubles. Barely above Vega is 4th-magnitude Epsilon (ε) Lyrae, the Double-Double. Epsilon forms one corner of a roughly equilateral triangle with Vega and Zeta (ζ) 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 any telescope. Delta (δ) Lyrae, upper left of Zeta, is a much wider and easier pair.
Friday, November 2
• Look for Capella sparkling low in the northeast these evenings. Look for the Pleiades cluster about three fists at arm's length to its right. These harbingers of the cold months rise higher as evening grows late.
Above the space between them are the stars of Perseus, astride the Milky Way.
Saturday, November 3
• Mars shines in the south after dark. Look barely 1° east (left) of it for Delta Capricorni, only a twentieth as bright at magnitude 2.8. A similar distance lower right of Mars is Gamma Cap, magnitude 3.6.
Sunday and Monday evenings Mars and Delta Cap will appear even closer: 0.6° apart.
• Daylight-saving time ends at 2 a.m. tonight in North America. Clocks fall back an hour. Showerthought: The old saying that clocks "spring forward" and "fall back" in those two seasons used to be metaphorical. The clocks did nothing; you had to change them. But now it's literally true: internet-connected clocks jump back and forth themselves.
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 guide to 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) and Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.
You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, or the bigger Night Sky Observer's Guide 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."
This Week's Planet Roundup
Mercury and Jupiter (magnitudes –0.2 and –1.7, respectively) are very low after sunset, just above the southwest horizon in bright twilight. Binoculars will help.
You'll catch brighter Jupiter first. On October 26th and 27th Mercury is about 4° below it. After that Jupiter sinks while Mercury moves to the left. By November 2nd Mercury is 6° more or less directly left of Jupiter.
Meanwhile fainter Antares, magnitude +1.0 and not quite gone, remains farther to their left, twinkling effortfully. Did I mention binoculars?
Venus is hidden deep in the glow of sunrise.
Mars (fading from magnitude –0.8 to –0.6 this week) shines highest in the south just after the end of twilight. It continues to set around 1 a.m.
In a telescope Mars is 12 arcseconds wide, and it's as gibbous as we ever see it: 86 percent sunlit. For a Mars map that displays which side is facing Earth at your time and date, use our Mars Profiler.
Saturn (magnitude +0.6, in Sagittarius) glows yellow low in the south-southwest in late twilight.
Uranus, near the Aries-Pisces border, is easy in binoculars at magnitude 5.7 — with a good finder chart, if you know the constellations well enough to see where to start with the chart.
Neptune, in Aquarius, is harder at magnitude 7.8. They're well up in the southeastern side of the sky soon after nightfall. Finder charts for Uranus and Neptune, or see the September Sky & Telescope, page 48.
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 that also depend on longitude (mainly Moon positions) are for North America.
Eastern Daylight Time (EDT) is Universal Time (also called UT, UTC, GMT, or Z time) minus 4 hours.
“This adventure is made possible by generations of searchers strictly adhering to a simple set of rules. Test ideas by experiments and observations. Build on those ideas that pass the test. Reject the ones that fail. Follow the evidence wherever it leads, and question everything. Accept these terms, and the cosmos is yours.”
— Neil deGrasse Tyson, 2014
"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
"Objective reality exists. Facts are often determinable. Vaccines save lives. Carbon dioxide warms the globe. Bacteria evolve to thwart antibiotics, because evolution. Science and reason are not a liberal conspiracy. They are how we determine facts. Civilization's survival depends on our ability, and willingness, to do this."
— Alan MacRobert, your Sky at a Glance editor
"Facts are stubborn things."
— John Adams, 1770