This Week’s Sky at a Glance, September 20 – 28 – Sky & Telescope

Friday, Sept. 20

• Cassiopeia shows its flattened-W form excessive within the northeast these evenings. The W is tilted left. To the traditional Greeks Cassiopeia was a legendary African queen. Her husband Cepheus, dimmer and extra sprawled out, is presently the subsequent constellation to her higher proper. Each lie alongside the winter Milky Approach.

• Within the middle of Cepheus, these moonless evenings are a very good time to convey out your binoculars or scope and check out for the unusually small, compact open cluster NGC 7160 — as Matt Wedel tells within the September Sky & Telescope, web page 43.

Saturday, Sept. 21

• Final-quarter Moon (actual at 10:41 p.m. Japanese Daylight Time). Tonight the Moon rises round midnight daylight-saving time, relying in your location. Look ahead to it to peek above the east-northeast horizon decrease proper of Capella and decrease left of the Pleiades.

By the primary signal of Sunday’s daybreak the Moon is shining excessive within the southeast, now with Orion to its decrease proper and Gemini to its decrease left. How typically do you look at the Moon together with your telescope when the Moon is its late-night waning phases? To most of us, the waxing Moon of night is far more acquainted — when lunar mountains and crater partitions solid their shadows in the wrong way.

Sunday, Sept. 22

• Fall begins late tonight; the September equinox happens at three:50 a.m. September 23rd EDT. That is when the Solar crosses the equator (Earth’s equator and subsequently the celestial equator too), heading south for the season. Dawn and sundown are very almost 12 hours aside, and the Solar rises and units virtually on the east and west factors in your horizon.

• Yearly round when summer season turns to autumn, Deneb takes over from brighter Vega because the zenith star after dusk (for skywatchers at mid-northern latitudes).

Monday, Sept. 23

• “My favourite observations enable me to make comparisons,” writes Matt Wedel within the October Sky & Telescope: “related objects at totally different distances, or objects of various sizes on the identical distance.” For binocular observers he affords some examples on the bowl of the Sagittarius Teaspoon, which is presently simply above the brilliant landmark Saturn. See his Binocular Spotlight column on web page 43 of the October difficulty.

Tuesday, Sept. 24

• Within the west, off to left of the Large Dipper, brilliant Arcturus, the “Spring Star,” shines a bit decrease at dusk every week. From Arcturus, the slim kite-shaped sample of Bootes extends 24° to the higher proper.

Wednesday, Sept. 25

• Earlier than and through daybreak on Thursday morning the 26th, look about three° proper of the crescent Moon for Regulus, as proven on the prime of this web page (for the center of North America). Binoculars will assist with Regulus because the sky begins to develop brilliant.

Thursday, Sept. 26

• At the moment of 12 months the wealthy Cygnus Milky Approach crosses the zenith in early night (for skywatchers at mid-northern latitudes). The Milky Approach extends straight up from the southwest horizon, passes overhead, and runs straight all the way down to the northeast.

Friday, Sept. 27

• Arcturus shines within the west as twilight fades out. Capella, equally brilliant, is barely rising within the north-northeast (relying in your latitude; the farther north you’re the larger it is going to be.) They’re each magnitude zero.

Later within the night, Arcturus and Capella shine on the identical top of their respective compass instructions. When will this occur? That is determined by each your latitude and longitude.

When it does, flip to look southwest. There will likely be Jupiter at about the identical top (relying in your latitude).

Look south-southeast, and there will likely be 1st-magnitude Fomalhaut about equally excessive too.

Saturday, Sept. 28

• The starry W of Cassiopeia stands excessive within the northeast after darkish. The suitable-hand aspect of the W, the brightest aspect, is tilted up.

Look alongside the second section of the W counting down from the highest. Discover the dim naked-eye stars alongside that section (not counting its two ends). The brightest of those, on the appropriate, is Eta Cassiopeiae, magnitude three.four. It is a Solar-like star simply 19 light-years away with an orange-dwarf companion, a stunning binary in a telescope.

The “one” on the left, fainter, is a naked-eye pair in a darkish sky: Upsilon¹ and Upsilon² Cassiopeiae, zero.three° aside. They’re orange giants unrelated to one another, 200 and 400 light-years away. Upsilon¹, barely fainter, is the farther one.

________________________

Need to turn out to be a greater astronomer? Be taught your method across the constellations. They’re the important thing to finding all the pieces fainter and deeper to hunt with binoculars or a telescope.

That is an outside nature pastime. For an easy-to-use constellation information masking the entire night sky, use the massive month-to-month map within the middle of every difficulty of Sky & Telescope, the important information to astronomy.

When you get a telescope, to place it to good use you will want an in depth, large-scale sky atlas (set of charts). The fundamental normal is the Pocket Sky Atlas (in both the original or Jumbo Edition), which reveals stars to magnitude 7.6.

Subsequent up is the bigger and deeper Sky Atlas 2000.0, plotting stars to magnitude eight.5; almost 3 times as many. The subsequent up, as soon as you realize your method round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) and Uranometria 2000.0 (stars to magnitude 9.75). And browse how to use sky charts with a telescope.

You may additionally desire a good deep-sky guidebook, similar to Sue French’s Deep-Sky Wonders assortment (which incorporates its personal charts), Sky Atlas 2000.0 Companion by Robust and Sinnott, or the larger Night Sky Observer’s Guide by Kepple and Sanner.

Can a computerized telescope substitute charts? Not for newbies, I do not assume, and never on mounts and tripods which might be lower than top-quality mechanically (that means heavy and costly). And as Terence Dickinson and Alan Dyer say of their Backyard Astronomer’s Guide, “A full appreciation of the universe can’t come with out growing the talents to seek out issues within the sky and understanding how the sky works. This information comes solely by spending time underneath the celebrities with star maps in hand.”

---

This Week’s Planet Roundup

Mercury, Venus, and Mars stay deep within the glare of the Solar.

Jupiter (magnitude –2.1, between the ft of Ophiuchus) is the white dot low within the south-southwest as twilight fades away. Orange Antares, a lot fainter at magnitude +1.zero, twinkles 9° to its decrease proper. It is a poor season for Jupiter telescopically. Not solely is the low-altitude seeing a large number, however Jupiter has shrunk to only 37 arcseconds huge.

Saturn (magnitude +zero.four, in Sagittarius) is the regular yellow “star” within the south throughout and simply after nightfall. It is 27° higher left of Jupiter. Beneath Saturn is the deal with of the Sagittarius Teapot. Barely above it’s the dimmer, smaller bowl of the Teaspoon.

Uranus (magnitude 5.7, in Aries) is properly up within the east by 10 or 11 p.m. daylight saving time and highest within the south round 2 or three a.m.

Neptune (magnitude 7.eight, in Aquarius) is properly up within the southeast by 9 or 10 p.m. and highest within the south round 11 or midnight. See Bob King’s article on observing Neptune and our 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 upon longitude (primarily Moon positions) are for North America.

Japanese Daylight Time (EDT) is Common Time (UT, UTC, GMT, or Z time) minus four hours.

_________________

Audio sky tour. Out underneath the night sky together with your earbuds in place, hearken to Kelly Beatty’s month-to-month podcast tour of the heavens above. It is free.

_________________

“The hazards of not pondering clearly are a lot larger now than ever earlier than. It isn’t that there is one thing new in our mind-set, it is that credulous and confused pondering might be far more deadly in methods it was by no means earlier than.”
— Carl Sagan, 1996