Moon, Jupiter, Saturn, Oct. 11-14, 2018
The waxing crescent Moon returns to evening twilight sky, posing with Jupiter and then Saturn. (The visibility of the fainter objects in bright twilight is exaggerated here.)

Friday, October 12

• Look lower left of the crescent Moon in twilight. Can you spot orange Antares, as shown here? For North Americans it's about 8° from the Moon, a little less than a fist at arm's length.

Way to the right of Antares shines brighter Jupiter.

• Then right around the end of twilight, you'll find zero-magnitude Arcturus shining low in the west-northwest at the same height as zero-magnitude Capella in the northeast.

When this happens, turn to the south-southeast, and there will be 1st-magnitude Fomalhaut at the same height too — if you're at latitude 43° north. Seen from south of that latitude Fomalhaut will appear higher; from north of there it will be lower.

That bright point far upper right of Fomalhaut is Mars.

Saturday, October 13

• The crescent Moon hangs in the southwest after sunset, as shown above. How early in the fading light can you spot Saturn, about 14° to the Moon's left?

Next, look for fainter, more difficult Antares about the same distance to the Moon's lower right.

• Vega is the brightest star very high in the west. After nightfall is complete, look to Vega's right by 14° (nearly a fist and a half at arm's length) for Eltanin, the nose of Draco the Dragon. The rest of Draco's fainter, lozenge-shaped head is a little farther right. Draco always eyes Vega!

Moon and Saturn, Oct 14-15, 2018
The Moon passing Saturn . . .

Sunday, October 14

• The "star" near the Moon tonight is Saturn, 3,900 times farther away.

• This being October, Deneb has replaced Vega as the zenith star after nightfall (for skywatchers at mid-northern latitudes). And, accordingly, dim Capricornus has replaced Sagittarius as the most notable constellation low in the south. Capricornus currently hosts bright Mars in its middle.

Monday, October 15

• The Big Dipper lies down horizontal low in the north-northwest late these evenings. How low? The farther south you are, the lower. Seen from 40° north (New York, Denver) even its bottom stars twinkle nearly ten degrees high. But at Miami (26° N) the entire Dipper skims along out of sight just below the northern horizon.

Tuesday, October 16

• First-quarter Moon (exact at 2:02 p.m. EDT). At nightfall the half-lit Moon shines in the south with Mars to its left, Saturn farther to its lower right, and Altair very high above it.

A finger-width above Altair is distant little Tarazed, magnitude 2.7.

Moon and Mars, Oct. 17-18, 2018
. . . and then it passes Mars.

Wednesday, October 17

• The Moon this evening shines to the right of Mars, 260 times farther away. Far to their lower left you'll find Fomalhaut (out of the frame here).

Thursday, October 18

• Now the Moon shines left (east) of Mars. Look to their lower left, by about two fists at arm's length, for Fomalhaut.

Friday, October 19

• The waxing gibbous Moon at dusk forms a right triangle (as seen from North America) with Mars to its right and Fomalhaut below it. Later in the evening, the triangle turns clockwise a bit as it wheels across the southern sky.

Saturday, October 20

• After dark, look upper left of the Moon, by two or three fists at arm's length, for the Great Square of Pegasus. It's standing on one corner and is a little more than a fist at arm's length in size.


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.

Jumbo Pocket Sky Atlas cover
The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and hundreds of telescopic galaxies, star clusters, and nebulae among them. Shown above is the Jumbo Edition for easier reading in the night. Sample chart.

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

Mars on October 10, 2018
Mars on October 10th, imaged by Christopher Go with a 14-inch scope. South is up. "Seeing was good today," he writes. "These images show Syrtis Major [the vertical dark 'peninsula' below center]. Hellas [the round bright area south of Syrtis Major] is the largest visible impact basin in the Solar System. Mare Tyrrhenum and Syrtis Minor [left of center] are well resolved. The Mitchel Mountains can be seen detached from the South Polar Cap."
Mercury and Venus are lost in the glare of the Sun.

Mars, moving eastward through central Capricornus, fades from magnitude –1.0 to –0.8 this week. It shines highest in the south soon after dark and sets around 1 a.m.

In a telescope Mars shrinks from 14 to 13 arcseconds wide this week, and it's as gibbous as we ever see it: only 86 percent sunlit. For a Mars map that displays which side is facing Earth at your time and date, use our Mars Profiler.

Jupiter (magnitude –1.8, in dim Libra) is very low in the west-southwest in mid-twilight and sets before twilight's end.

Can you still make out fainter Antares, magnitude +1.0, about 14° to Jupiter's left?

A bigger challenge: Can you detect fainter Delta (δ) Scorpii, currently magnitude +1.8 (it's variable), about midway between the two? Binoculars help. See the illustration at the top of this page.

Saturn (magnitude +0.5, in Sagittarius) glows yellow in the south-southwest in late dusk. It's about four fists at arm's length to the lower right of Mars.

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.

Neptune, in Aquarius, is harder at magnitude 7.8. By mid-evening they're well up in the east and southeast, respectively. 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.


"Rational and innocent entertainment of the highest kind."
— John Mills, 19th century Scottish manufacturer and founder of Mills Observatory, on amateur astronomy.


"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


Image of Bill -Simpson

Bill -Simpson

October 15, 2018 at 10:12 pm

After finally getting my 17.5 inch Dob back together after fixing the damage to the bottom of the mirror done in shipping with some epoxy, I was fooling around with Stellarium, and noticed it read out the apparent number of degrees above the horizon an object was, based on my location. I thought there must be something that I could attach to the telescope which would show the angle of the telescope in relation to the earth's surface. Sure enough, for $8, I bought a 'Johnson Level & Tool 750 pitch and slope locator' on Amazon. Contractors use it for measuring roof pitches and slopes of various surfaces like driveways. One side gives roof pitches, and the other reads out in degrees.
I had to decide where, and how, to attach it to the telescope which lives in my garage all assembled with steel wheelbarrow handles attached, so I can roll it right out into the light pollution on Clearwood Drive in Slidell on the few nights when it isn't cloudy, or when they aren't spraying for mosquitoes like they just did. I think they passed twice tonight! Oily spray and telescope mirrors don't mix, so I'm always ready to make a hasty retreat whenever I hear the truck on a nearby street.
Anyway, I decided to attach the slope gauge to the bottom of the top ring of the upper cage assembly. It is all plastic, so hot melt glue can easily keep it stuck to the top wooden ring. I did a test tilt down to make sure to locate it so that it remained perpendicular to the ground, so the needle pointer wouldn't hang up as the tube tilted up and down. I made some pencil marks so as to place it correctly before the hot melt glue hardened. It won't be too accurate, but it has to beat trying to eyeball 27 degrees above the horizon. And it doesn't need any batteries.
The next project will be trying to get my neighbor to aim his floodlight about 10 degrees more to the west. He had better cooperate, or I'll revoke his parking on my second driveway privileges. I got the local utility to put a cutoff shield on the nearest streetlight. Too bad the tornado that hit next door during Hurricane Katrina twisted the fixture enough to still let some light hit my driveway. Now what are the chances of that? At least 90% of the light is blocked. Those new bulbs with the mixture of gasses which produce white light are some bright.

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mary beth

October 17, 2018 at 10:49 am


Very entertaining story! You’ll have to keep us posted when you finally get to test it. I had no idea you could get the utility company to put a cut off shield on a streetlight. I’m going to see if they’ll do that here in Houston, one ‘new fangled’ bright one right across the street. My favorite part of the story was about the floodlight. . Sounds like y’all are generous neighbors with the parking lol. Looks like it’s going to be cloudy in both our neck of the woods for a get more days, but maybe next week, we’ll get some clear starry nights! Enjoy!

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October 17, 2018 at 9:58 pm

"Wednesday, October 17 • The Moon this evening shines to the right of Mars, 260 times farther away."

It was a lovely evening where I am at tonight. Mars was about 6 degrees from the waxing gibbous Moon and the star, Eta Capricorni was near 1 degree from Mars tonight. Both were visible in the same field of view at 31x and easy with binoculars. Since Mars stopped retrograde in Sagittarius on 28-Aug-18, Mars has moved some 15 degrees eastward along the ecliptic. I viewed tonight using my 90-mm refractor, Mars views from 31x to 180x. Distinct gibbous shape with hint of polar caps and some surface area, even at 13 arcsecond size or so. Central meridian of Mars was near 36 degrees when I viewed 2030 EDT and shortly after. I also enjoyed some lunar views in the northern region near the crater Anaxagoras. Mary beth, on 12-Oct-18 using my 10-inch, I had some great views of M31 galaxy and the Perseus Double Cluster. We are enjoying October skies here now, colder nights with temps in 40s and later 30s this week. I have been busy with my STIHL chain saw, double bladed axe, and plenty of logging splitting 🙂

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mary beth

October 18, 2018 at 8:55 pm

Hi Rod! That all sounds magnificent! Mars has been such a treat this year. So glad you’re having clear skies and cool weather, the views must be amazing. I’m missing Venus aren’t you? You sure have had cool temperatures, the lowest we’ve had is about 55° and that was only for one day. I’d love to have four seasons, like Herman Melville said, “there is no quality except by contrast“. I hope you all stay cozy and have plenty of clear nights and lots of cozy fires. I am enjoying watching Formalhaut, and was pleasantly surprised by Capella the other night. And don’t forget to check out the “ghost of the summer suns” next week. Love how S&T makes the holidays fun!

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October 18, 2018 at 9:09 pm

mary beth, yes it has been some great viewing lately (September not as good). *lots of cozy fires*. I have a wood burning stove and also an outdoor fire pit area. Sitting outside under the night stars on a bench log when it is cold with open fire, cowboy cooking tripod, chain, and cowboy coffee 🙂 I can drop the horseshoe into the pot and tell when it is ready. The horseshoe will stand up 🙂

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mary beth

October 19, 2018 at 6:03 pm

Haha! I had to Google that one LOL! I might be able to handle cowboy coffee as long as there’s Half&half available. Sounds like a fun life, the way it should be: lots of outdoor time enjoying all the beauty of the four seasons, of day and night! See you on next week’s column!

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