Astronomy.com blog : constellation

Try these weekend observing targets

David Eicher — Fri, 20 Nov 2009 17:28:00 GMT

Did you ever find yourself out under a clear, dark sky in November wondering what to look at? How about targeting a few objects in the constellation Pegasus, one of my favorite autumn constellations. Here are some suggestions:

Galaxy NGC 7479 is one of the most popular objects for viewing in the constellation, as it shows a distinct, nearly face-on barred spiral structure. Photos of NGC 7479 appear frequently in astronomy magazines and on the web and give this object a familiar form. This galaxy lies at the end of a long string of stars that appear starkly to viewers with a 3-inch scope. In a 6-inch scope, this galaxy appears as a bar with a faint haze surrounding it. Larger scopes show much more detail, however, including the asymmetrical arms arcing away from the central glow.

How about targeting the two most conspicuous members of the Pegasus I galaxy cluster (pictured at right)? NGC 7619 and NGC 7626 are worth viewing even in small scopes. The galaxies lie just 7 arcminutes apart; the former shows a bright starlike nucleus while NGC 7626 has a tiny center.

If novelty’s your game, you could also target the first two objects in the NGC — NGC 1 and NGC 2. These galaxies are just 1.8' apart and are easily visible in a 6-inch scope under a dark sky.

Have you ever seen these galaxies? Do you spend time tracking down deep-sky objects in Pegasus? Let us know what your favorite November sky objects are and what you’re viewing them with.

Additional online observing resources from Astronomy magazine:

StarDome — Our interactive star chart helps you create an accurate map of your sky. This tool will help you locate these targets.
Video: Observe easy to find objects in the autumn sky, with Senior Editor Rich Talcott
Video: Autumn observing targets for small telescopes, with Senior Editor Michael E. Bakich [available to magazine subscribers]
Video: Autumn observing targets for large telescopes, with Editor David J. Eicher [available to magazine subscribers]
Podcast: Weekly observing targets, with Senior Editor Michael E. Bakich [available for free to registered members of Astronomy.com]

July 17-24, 2009: The Coathanger, globular cluster M22, the Phantom Streak

Michael Bakich — Thu, 16 Jul 2009 20:14:00 GMT

Each week, Astronomy magazine Senior Editor Michael Bakich, a master at explaining how to observe, posts a podcast about three objects or events you can see in the sky.

In each episode, Michael highlights:

One object you can see without any optical aid
One object you can see with a small (4-inch) telescope
One object you can see with at least an 8-inch telescope

Targets for July 17-24, 2009

Naked eye:

Small telescope:

8-inch or larger telescope:

The weekly observing podcast is available to registered members of Astronomy.com. The podcast remains FREE, so please register with the site to make sure you don't miss an episode!

Listen to this week's podcast.

This week's podcast is brought to you by Celestron — one of the world's leading designer and manufacturer of high-quality optical equipment. Learn more about Celestron and their products at www.Celestron.com.

Send us your astronomy questions

Liz Kruesi — Wed, 15 Jul 2009 21:05:00 GMT

Perplexed by planets? Confused by cosmology? Baffled by black holes? Then send in your questions to Astronomy magazine at askastro@astronomy.com.

If you have an astronomy question about observing, the planets, stars, cosmology, or astronomy history, send it in! Five are selected each month for publication in the Ask Astro section of Astronomy magazine. If your question is selected, we will forward it to an expert for his or her response. Then, the question and answer will appear together in a future issue. We may edit or revise your question for clarity.

We aren’t always able to respond to questions individually. But please keep the questions coming — they help us to learn what our readers are interested in, and what topics we should consider for future coverage in the magazine.

July 10-17, 2009: The Teapot of Sagittarius, globular cluster M4, the Snake Nebula

Michael Bakich — Thu, 09 Jul 2009 19:34:00 GMT

Each week, Astronomy magazine Senior Editor Michael Bakich, a master at explaining how to observe, posts a podcast about three objects or events you can see in the sky.

In each episode, Michael highlights:

One object you can see without any optical aid
One object you can see with a small (4-inch) telescope
One object you can see with at least an 8-inch telescope

Targets for July 10-17, 2009

Naked eye:

Small telescope:

8-inch or larger telescope:

The weekly observing podcast is available to registered members of Astronomy.com. The podcast remains FREE, so please register with the site to make sure you don't miss an episode!

Listen to this week's podcast.

April 10-17, 2009: The Y of Virgo, globular cluster M3, and spiral galaxy NGC 4731

Michael Bakich — Thu, 09 Apr 2009 19:28:00 GMT

Here is the transcript for my podcast about how to see the Y of constellation Virgo, globular cluster M3, and spiral galaxy NGC 4731 this week.

Check out the Astronomy.com's interactive star chart — StarDome — to see an accurate map of your sky. It'll help you locate some of this week's key targets. Astronomy magazine subscribers have access to a slew of cool functions with StarDome PLUS.

Each week, I highlight three different night-sky targets for you to see:

One object you can find with your naked eyes or through binoculars
One object to find with a small telescope
One deep-sky object to find with an 8-inch or larger telescope for you avid astronomers

--Start transcript--

Alphabet soup
This week’s naked-eye object is a large asterism in the constellation Virgo called the Y. It’s made up of six stars, the faintest of which still shines brighter than 4th magnitude, so you’ll see it easily even from the suburbs.

Start at Virgo’s brightest star, Spica (Alpha [α] Virginis). This blue-white 1st-magnitude luminary marks the bottom of the Y. From Spica, move 14.5° northwest to magnitude 2.7 Porrima (Gamma [γ] Virginis).

From Porrima, the Y branches in two directions, toward the north-northeast and the west-northwest. And if you’re a fan of strange star names, you’ll enjoy these. The north-northeast leg contains Minelauva (Delta [δ] Virginis) and Vindemiatrix (Epsilon [ε] Virginis). The west-northwest branch contains Zaniah (Eta [η] Virginis) and Zavijava (Beta [β] Virginis).

So many stars
This week’s small telescope target is globular cluster M3 in the constellation Canes Venatici the Hunting Dogs. To find it, start at the brilliant star Arcturus (Alpha [α] Boötis). Draw a line 25° long up to the northwest until you hit Cor Caroli (Alpha Canum Venaticorum). M3 lies near the midpoint of this line.

No other bright deep-sky object lies nearby, so you’ll have no trouble zeroing in on M3. And, here’s a test for you sharp-eyed observers: Try to spot M3 without optical aid from a dark site. At magnitude 6.3, it’s a tough naked-eye catch, but many observers have seen it, so it’s not impossible.

M3 looks great even through a 4-inch telescope. The cluster has a wide, bright center that accounts for about half of this object’s width. Surrounding the center are dozens of stars whose density gradually decreases with their distance from M3’s core.

Start with a magnification around 100x and increase the power if the steadiness of the air warrants it. M3 isn’t small — its overall size is half that of the Full Moon — but it is dense. Through ever-larger scopes, you’ll resolve more and more stars in this amazing cluster.

S marks the spot
This week’s deep-sky object is spiral galaxy NGC 4731 in Virgo. It’s not a bright galaxy — only magnitude 11.3 — but it has several features I think you’ll find worth your observing time. NGC 4731 lies 3.3° east-northeast of magnitude 4.7 Chi (χ) Virginis.

This dim galaxy appears highly distorted into an “S” shape because it doesn’t travel through space alone. You’ll easily spot its brighter companion. Look only 0.8° to the northwest for magnitude 9.2 NGC 4697. Gravitational interaction with this elliptical galaxy has nearly destroyed NGC 4731’s spiral arms.

Through a 10-inch telescope, observe NGC 4731’s long, relatively bright central bar. If your observing site is dark enough, crank up the power past 200x, and look at the wide, irregular spiral arms that originate from each side of the bar. The western arm appears somewhat brighter. Tiny bright patches within both arms signal the existence of hotspots of star formation. Through a 20-inch or larger telescope, use a nebular filter to increase the contrast of those regions and the galaxy’s already formed stars.

At an estimated distance of 65 million light-years, NGC 4731 sits on the far side of the Virgo Cluster of galaxies.

--End transcript--

Previous episode: The Broken Engagement Ring, globular cluster M68, and the Helix Galaxy

March 20-27, 2009: Constellation Canes Venatici, the Whirlpool Galaxy, the Whale Galaxy

Michael Bakich — Thu, 19 Mar 2009 20:12:00 GMT

Here is the transcript for my podcast about how to see the constellation Canes Venatici, the Whirlpool Galaxy, and the Whale Galaxy this week.

Each week, I highlight three different night-sky targets for you to see:

One object you can find with your naked eyes or through binoculars
One object to find with a small telescope
One deep-sky object to find with an 8-inch or larger telescope for you avid astronomers

--Start transcript--

Hunt for the Hunting Dogs
This week’s naked-eye object is the difficult-to-see constellation Canes Venatici the Hunting Dogs. This constellation only has three bordering star patterns: Ursa Major the Great Bear lies to the north and west; Coma Berenices the Hair of Berenice forms part of its southern border; and Boötes the Herdsman lies to the east and also completes the southern border.

In size, Canes Venatici ranks 38th out of the 88 constellations that cover the sky. It occupies 465 square degrees — that’s a respectable 1.13 percent of the sky.

The best time to see Canes Venatici is early April. That’s when the constellation lies opposite the Sun. It rises at sunset, sets at sunrise, and is visible in the sky all night. The worst time to look for Canes Venatici is in early October. That’s when its stars line up with the Sun.

Canes Venatici bustles with deep-sky objects. It contains five Messier objects within its borders: globular cluster M3, and spiral galaxies M51, M63, M94, and M106.

Finding Canes Venatici isn’t easy. It’s rated as the 5th faintest constellation in the sky. From a dark site, look just below the Big Dipper’s handle. The brightest star in this region — and that’s not saying much — is Cor Caroli (Alpha [α] Canum Venaticorum), which shines at magnitude 2.8. Canes Venatici’s only other reasonably bright star, Chara (Beta [β] Canum Venaticorum) lies 5° to the west-northwest and glows weakly at magnitude 4.3.

The sky’s best galaxy?
This week’s small telescope target is the spectacular Whirlpool Galaxy in my featured constellation, Canes Venatici. Also known as M51, the Whirlpool lies one-quarter of the way from magnitude 1.8 Alkaid (Eta [η] Ursae Majoris) to Cor Caroli.

Through a 4-inch telescope under a dark sky, you’ll see a circular glow with a bright core. A small bright area lies outside the fuzzy circle. That’s NGC 5195, a companion galaxy of M51. Although photographs appear to show a connecting arm between the two galaxies, this is an illusion.

Computer models indicate NGC 5195 passed close to the Whirlpool’s disk some 70 million years ago and then plunged through its plane. A 6-inch scope will begin to reveal M51’s spiral arms.

In 1845, William, Third Earl of Rosse, saw the spiral form of this object through his 72-inch reflector. M51 was the first galaxy to show such structure.

Thar’ she blows!
This week’s deep-sky target — also in Canes Venatici — is the Whale Galaxy, also known as NGC 4631. This magnificent edge-on galaxy sits 6.5° south-southwest of Cor Caroli.

The Whale Galaxy shines at magnitude 9.2. It measures 15' long and 3' wide at its thickest point. Now, here’s a celestial object an 8-inch telescope will do justice to. Under a dark sky, use a magnification around 200x.

The central region shines brightest, and the spiral arms have a mottled, salt-and-pepper appearance because of vast quantities of dust. The easternmost arm is much thicker than the one to the west. A tiny southern extension gives it the appearance of an arrowhead. The western arm tapers away from the core more gradually.

As you’ll probably notice, the Whale doesn’t swim through space alone. Look only 2.5' northwest of NGC 4631 for NGC 4627. This magnitude 12.0 dwarf elliptical galaxy has interacted with the Whale in the past, triggering intense star formation. In fact, the small galaxy is responsible for the irregular appearance of its large companion.

--End transcript--

Previous episode: Constellation Corvus the Crow, open cluster M67, and spiral galaxy NGC 2683

March 13-20, 2009: Constellation Corvus the Crow, open cluster M67, and spiral galaxy NGC 2683

Michael Bakich — Thu, 12 Mar 2009 20:44:00 GMT

Here is the transcript for my podcast about how to see the constellation Corvus, open cluster M67, and spiral galaxy NGC 2683 this week.

Each week, I highlight three different night-sky targets for you to see:

One object you can find with your naked eyes or through binoculars
One object to find with a small telescope
One deep-sky object to find with an 8-inch or larger telescope for you avid astronomers

--Start transcript--

A southerly crow
This week’s first object is the small but easy-to-see constellation Corvus the Crow. This constellation only has three bordering star patterns: Virgo the Maiden lies to the north and east; Crater the Cup lies to the west; and Hydra the Water Snake sits to the south. In size, little Corvus ranks 70th out of the 88 constellations that cover the sky. It occupies 184 square degrees — that’s only 0.45 percent of the sky.

One meteor shower’s radiant lies within Corvus. The Corvids peak June 26. The best date to see Corvus is March 28. That’s when the constellation lies opposite the Sun. It rises at sunset, sets at sunrise, and is visible in the sky all night. The worst date to look for Corvus is September 27. That’s when its stars line up with the Sun.

Although Corvus has no Messier object within its borders, it’s a near miss. Just to the constellation’s north, in Virgo, is one of the best galaxies in the sky. It’s the Sombrero Galaxy, also known as M104. Check it out through a small or (preferably) large telescope.

Finally, you can use Corvus’ top two stars as pointers to a bright blue luminary. Draw a line from magnitude 2.6 Gienah (Gamma [γ] Corvi) through magnitude 2.9 Algorab (Delta [δ] Corvi), and extend that line 4 times the distance between the two stars, and you’ll arrive at Spica, the brightest star in Virgo.

Cancer’s “other” cluster
This week’s small telescope target is not the Beehive Cluster in Cancer. It’s that constellation’s other open cluster, M67 (pictured above at right, courtesy Anthony Ayiomamitis). You’ll find it easily through binoculars or a small telescope 1.7° due west of magnitude 4.3 Alpha (α) Cancri.

Through a 4-inch telescope, you’ll resolve roughly 2 dozen stars in M67 across an area two-thirds the width of the Full Moon. Increase the aperture to 6 inches, and 50 stars will shine forth.

A dozen of M67’s stars shine brighter than 11th magnitude. When you view the Beehive through a telescope, you’ll note the yellow star on its northeastern edge. Identified as SAO 98178, this star shines at magnitude 7.8 but is not a member of the cluster.

Diamond in the rough
This week’s deep-sky object lies in a constellation even more difficult to find than Cancer — Lynx. The obscure star group lies due north of Cancer and stretches to the northwest from there.

NGC 2683 is a spiral galaxy, and a relatively bright one at that. Shining at magnitude 9.8, you can spot it through a 3-inch telescope from a dark observing site. To pull out its details, however, you’ll need a bigger scope.

This galaxy is a classic edge-on spiral that orients exactly northeast to southwest. It appears more than three times as long as it is wide with an extended, bright central region. The faint spiral arms begin to show alternate dark and bright patches called mottling through a 12-inch telescope. Through even larger scopes, you’ll notice that the northeastern arm extends a bit farther than the southwestern one.

---End transcript--

Previous episode: Head of Hydra, NGC 1981, and NGC 1999
Previous transcript

New videos: Springtime observing targets

Rich Talcott — Tue, 10 Mar 2009 21:10:00 GMT

In this video, I discuss the objects you can see with your naked eyes and binoculars in this spring’s sky. The season offers several bright planets, notable constellations, and bright deep-sky objects. You can locate all the night-sky sights I talk about with Astronomy.com's interactive star chart StarDome.

Watch the video, "Observe easy-to-find objects in the spring sky."

Venus

As darkness falls during the first half of March, your eyes will be drawn to the western sky. In the deepening twilight, Venus gleams like nothing else. You won’t have any trouble identifying the brilliant planet, which glows brighter than any other point of light in the sky. Venus passes between the Sun and Earth in late March, and will reappear in the east before dawn by mid-April.

Saturn

Beautiful Saturn also lies in the evening sky, although it doesn’t stand out like Venus. Look for Saturn among the background stars of Leo the Lion, where it glows as bright as that constellation’s brightest star, Regulus. Saturn will remain in the evening sky until late summer.

Mercury

Elusive Mercury puts on its best evening show of the year in the last 10 days of April. Watch for a bright point of light low in the west-northwest 30 to 45 minutes after the Sun sets. The easiest evening to spot it will be April 26, when it lies directly below a crescent Moon.

Jupiter

Meanwhile, Jupiter appears conspicuous in the morning sky during April and May. Look for it in the southeast around the time twilight starts to paint the sky. Only the planet Venus shines brighter than Jupiter.

The Big Dipper

Spring’s starry background has its own charm. Those of us in the Northern Hemisphere have a signpost in the spring sky: the bright asterism of the Big Dipper. Seven bright stars in the constellation Ursa Major the Great Bear create the Dipper’s shape. On spring evenings, the Dipper stands nearly overhead, at the center of this star chart.

Use the two stars at the end of the Dipper’s bowl, called the Pointers, to lead you to the North Star, Polaris. Extend the line between the Pointers (which lie at the bottom left of this photo), and extend it about five times that distance. Polaris is the brightest star in the Little Dipper and forms the tip of its handle.

Head back to the Big Dipper and take a close look at the middle star in the handle, called Mizar. If you have decent eyesight, you should see a fainter companion star just to its east. If you can’t see it, turn your binoculars on this star and its double nature will stand out.

Now, let’s use the Big Dipper to find some of spring’s other celestial delights.

If you follow the arc of the Dipper’s handle away from the bowl, you’ll soon arrive at Arcturus — the brightest star in the spring sky. Continue the arc about an equal distance and you’ll find Spica, the brightest star in the constellation Virgo. Spica dominates this sprawling constellation, and has the distinction of being the bluest of all 1st-magnitude stars. When it comes to stars, blue means hot, and Spica’s surface blazes at a temperature nearly four times hotter than the Sun.

Next, head back to the Big Dipper, and imagine poking a hole in the bottom of its bowl. The water would flow out and fall on the back of Leo the Lion. Leo consists of two distinctive sections: A group of six stars on the right that looks like a backward question mark, and three stars on the left that form a right triangle. Remember that Saturn augments the Lion’s shape this year, just below the pattern seen here.

Our final stop in the spring sky lies one constellation west of Leo, in the faint group known as Cancer the Crab. Smack in the middle of this constellation lies perhaps the spring sky’s finest binocular target: the Beehive star cluster (M44). On exceptionally clear nights from a dark site, you might spot the Beehive with your naked eyes. Binoculars reveal the cluster’s true nature. Through 10x50 binoculars, you should be able to see at least two dozen stars packed into a circle some three times wider than the Full Moon. It’s a sight you won’t soon forget.

We’ve created two more videos like this one to help you enjoy everything the springtime sky has to offer.

Astronomy magazine Senior Editor Michael Bakich’s video “Springtime observing for small telescopes” highlights this year’s best springtime targets you can see with a 4-inch or smaller telescope.

Astronomy magazine Editor Dave Eicher’s video “Springtime observing for large telescopes, 2009” highlights this year’s best springtime deep-sky objects you can see with an 8-inch or larger telescope. Both of these videos are available for Astronomy magazine subscribers at Astronomy.com/videos.

I’ll be back again this summer to talk about what’s on view during the warmest nights of the year.

March 6-13, 2009: Head of Hydra, NGC 1981, and NGC 1999

Michael Bakich — Wed, 04 Mar 2009 22:15:00 GMT

Here is the transcript for my podcast about how to see the Head of Hydra, open cluster NGC 1981, and reflection nebula NGC 1999 this week.

Each week, I highlight three different night-sky targets for you to see:

One object you can find with your naked eyes or through binoculars
One object to find with a small telescope
One deep-sky object to find with an 8-inch or larger telescope for you avid astronomers

--Start transcript--

Head of the class
This week’s naked-eye object is the Head of Hydra (pictured at right). This asterism marks the westernmost part of the sky’s largest constellation.

The Head of Hydra lies 2° due south of the midpoint of a line that joins Procyon (Alpha [α] Canis Minoris) and Regulus (Alpha Leonis). Unless you live under the worst light pollution, you’ll see the Head with your naked eyes.

Six stars form the asterism. The brightest is magnitude 3.1 Zeta (ζ) Hydrae. From there, move west to Epsilon (ε) and Delta (δ) Hydrae. Then swing back east to Rho (ρ) Hydrae. Drop 3.5° southwest to Sigma (σ) Hydrae. At magnitude 4.4, this is the faintest star in the asterism. Finally, head east again to the sixth and final star, Eta (η) Hydrae.

Avert your gaze
This week’s small telescope target is open cluster NGC 1981 in Orion. To locate this easy-to-see object, first find the Orion Nebula (M42). After you’ve soaked up the view from that celestial wonder, look 1° due north.

NGC 1981 is a bright open cluster. Its magnitude, 4.2, ties it for 11th place among open star clusters. It’s large, too. NGC 1891’s diameter is nearly that of the Full Moon.

When you observe NGC 1891 through a small telescope, use a magnification near 100x. Be sure to segregate the stars of the cluster from the surrounding star field. Note that the curved line of three magnitude 6.5 stars just to the east do not belong to the cluster.

Through a mirror, dimly
This week’s deep-sky object is reflection nebula NGC 1999 in Orion. You also can easily find this object by starting at the Orion Nebula. Move your telescope just a bit more than 1° south-southeast of M42, and your field of view will sweep up NGC 1999.

This reflection nebula has a triangular shape, but there’s more. A dark, irregular bar obscures much of the bluish light near NGC 1999’s center. This dark cloud is a Bok globule, a region of dust and cold gas — possibly a star-forming region — that obscures the light from objects behind it. Astronomers named such globules for Dutch-born American astronomer Bart Jan Bok (1906–1983), who pioneered their study.

NGC 1999’s illumination comes from the star V380 Orionis. It sits just outside and to the east-southeast of the dark central region. The star is so young that the reflection nebula NGC 1999 is material left over from the star’s formation.

---End transcript--

Previous episode: Constellation Columba, globular cluster NGC 1851, and spiral galaxy NGC 1808
Previous transcript

The perfect deep-sky observing guide

Rich Talcott — Wed, 04 Mar 2009 20:34:00 GMT

A dark night and a small- to medium-sized telescope are all you need to enjoy the deep-sky splendors that dot Earth’s skies. Oh, and one other thing — a good guide that describes what to look for and what you’ll see through the eyepiece.

We’re excited to offer one of the best deep-sky observing guides of the past decade. Author and Astronomy magazine Contributing Editor Tom Polakis created an exclusive series of articles for the magazine called “Celestial Portraits.” The series ran in Astronomy from April 1998 through March 2004, and now you can purchase and download the whole series in digital format.

In each of the 45 articles, Polakis features one or more constellations and the sparkling star clusters, glowing gas clouds, stately galaxies, and other deep-sky objects that backyard astronomers can’t get enough of. In addition to detailed descriptions, each article features great amateur photos and a star chart that pinpoints every object’s location.

We put together 11 packages, and each contains four articles from the series.

To browse the catalog, visit Astronomy.com’s new “Constellation Observing” section. There you can find your favorite constellation, preview each article, see what constellations each package contains, and download “Orion the Hunter” for free.

Keep your eyes peeled for more downloadable articles just like these from Astronomy magazine.