Podcaster: Ralph & Paul
Title : Awesome Astronomy’s September Sky Guide
Organization: Awesome Astronomy
Link : www.awesomeastronomy.com
Description: What to look out, and up, for in September. We start with the constellation of Cassiopeia in our beginners’ and young observers’ challenge. Next up is planets, the phases and conjunctions of the moon to enjoy this month. We then round up the best of the deep sky offerings for the month with the large clusters and a nice easy nebula in the constellation Sagitta & Vulpecula.
For those in the Southern Hemisphere, 365 Days of Astronomy also play Alice Enevolsen’s What’s Up Tonight, Southern Skies Edition each month.
Bio: Awesome Astronomy is the show for anyone and everyone who has even the slightest interest in astronomy and science.
Join Ralph & Paul twice each month, for informative and fun astronomy programs telling you what to look out (and up) for every month. You can be guaranteed a passion for astronomy, simple explanations of complex and fundamental topics, space and science news, absorbing interviews with astronomers who make the news and listeners’ astronomy questions answered
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Transcript:
Paul: Finally September is here. Those awful bright sunny evenings and short nights are behind us and the new astronomy season kicks off like a new term at school. So break out your shiny new pencil case, carve your name into your brand-new calculator with your compass and sit back and let us take you through the delights that await you in this months sky. We have a very close lunar/planetary encounter and a chance to compare a planet to a stellar rival, but first Ralph, what have you got lined up for our beginners guide this month?
Ralph: Well, for the beginners and young astronomers this month, we’re looking at the constellation represented by Queen Cassiopeia. Difficult to spell, nice to say and unmistakable in the north eastern sky this month, Cassiopeia’s already well above the horizon as soon as it’s dark and sits not far from the zenith by 2am.
Looking north east, the very obvious W-shape of 5 bright stars marks the region we’re visiting this month and just a random scan of the area with a small telescope will reveal some of the finest open star clusters anywhere in the sky, making Cassiopeia particularly good for binocular observing.
And we’ll start off with one of the few clusters whose discovery can be attributed to female astronomer, Caroline Herschel.
The two stars that form the right hand line in the W-shape are called Shedir (at the bottom of the stroke) and Caph at the top. Look for the next brightest star to the right of Caph – about two outstretched fingers’ width away, called rho cassiopeiae, and less than a degree away and easily within the same field of view of a low power eyepiece or a pair of binoculars sits NGC 7789. Also known as Caroline’s Rose, see if you can make out the rose shape caused by dark voids between the stars. These stars were all formed at the same time but the larger ones have exhausted their hydrogen, bloated and therefore provide some contrasting colour to the rose.
Next up we have an open cluster discovered by Caroline’s brother, William Herschel, and possibly the most popular cluster in Cassiopeia – especially since 1982 because we’re looking for NGC 457, also known as the ET cluster.
Draw a line from the top left hand star, epsilon Cassiopeiae, to the left hand bottom star in the W shape, Ruchbar, if you follow this line for a further 2 degrees right of Ruchbar, you’ll notice two bright stars that look like eyes (giving rise to the more conventional Owl cluster moniker). centre these two stars in your eyepiece and the body and wings of the owl should emerge. Look really hard, use your imagination and wave a magic wand and you might be able to convince yourself that you’re also seeing Steven Spielberg’s ET instead of an owl
Finally, I have a bit more of a challenge, but one that’s worth it.
Draw a line between Shedar, the bottom right hand star in the W shape, and the Andromeda galaxy – which sits an out streched hand’s width to the east of Shedar and will be visible as a large smudge to the naked eye in dark skies. Roughly half way along this line is NGC 185 a dwarf elliptical galaxy of similar apparent size to the two previous clusters. At magnitude 10, it’s quite a challenge and it’ll only appear as an oval smudge in the eyepiece, but what you’re seeing here is a satellite galaxy of the Andromeda Galaxy which has a feeding black hole in its centre. Being beyond our own Milky Way, this galaxy is 285 times further away than the star clusters I’ve just suggested.
Paul:Now Ralph has wetted your appetite let’s take a look at what is happening in our Solar System this month
The stars of the planetary show at the start of september are certainly Mars and Saturn, not really telescopically as they are both way past opposition but they open the month as a pair in libra but move apart rapidly.Look out though for a chance to compare Mars to it’s rival antares on the 28th and you will understand where the star got it’s name from.
Venus is still the morning star but as we work through the month the second planet is on the move towards the suns glare and by months end will rise just an hour before dawn.
Jupiter is making it’s presence felt in the predawn sky rising around 2am UT in the constellation cancer. Not a long observation window but if you’ve missed the king of the skies over the summer then it might be worth an early morning or long night.
Uranus is well placed this month and can be found in pisces rising around 7pm UT. As I always point out unless you have a large scope there isn’t much to see but the greenblue disc is a pleasing sight and the knowledge you are seeing one of the most distant planets make the view all the better. Look out for a close encounter with the moon on the night of 10/11 at 1.20am UT For those in the far north, such as the Shetlands in the UK you will see the moon occult Uranus.
If looking at distant planets is your thing then try Neptune in Aquarius, like uranus no detail to be seen but we are not far past opposition so the view is about as good as it gets.
We start September with a bright evening moon that reaches first quarter on the night of the 2nd at 11.11am UT, full moon follows on the 9th at 1.38am UT, whie the earlier half of the night gets back to dark skies as we hit last quarter on the 16th at 2.05am UT, and return once more to new moon on the 24th at 6.14am UT.
Other than those already mentioned we have lunar encounters with the hyades cluster on the night of the 14/15th, the morning sky on the 20th sees jupiter paired up with the moon. saturn is near the evening waxing crescent on the 27th followed by mars and antares on the 29th.
For our deep sky challenge this month you are getting a two for one deal in the shape of the constellations of Sagitta and Vulpecula, the arrow and the little fox.
Sagitta, the arrow fired by nearby hercules to kill aquilla the eagle who had a bit of a fetish for Prometheus’ liver is the third smallest constellation and and sits within the summer triangle. As you move up from altair at the base of the triangle towards deneb in Cygnus look for a small line of mag three stars with a distinctive triangle to the right, essentially making it look like an arrow. It is not an impressive constellation but within it is the often over looked M71. Not a messier often mentioned in conversation but a great target and one that until the 1970s was classified wrongly as an open cluster, more modern techniques and greater understanding saw M71 reclassified as loose globular cluster. It is young for the type (hence the earlier confusion) and is only 12000 light years away and 27 light years across. It lacks the typical dense core of a glob and it makes for an interesting comparison with that nearby archetype M13.
Vulpecula is the little fox surfing the arrow. Moving a little further towards cygnus is the very indistinct collection of mag 4 stars that to the eyes makes anything but a fox. The constellation stretches across the centre of the summer triangle and is larger than the scattering of it’s brightest stars suggest. This is a cunning fox and hidden inside are two gems of the sky NGC6853 or M27 and Collinder 399 or Brocchis cluster. M27 better known as the dumb bell nebula is a planetary nebula about 1300 light years away and in a good sky is visible in binoculars at 8 arcminutes across and magnitude 7.5. That said M27 is an object that seems particularly vulnerable to light pollution and I have found it be a sensitive little soul when it comes to sky conditions. It is an impressive object and when seen set against the dense star field of the milkyway it is one of the skies real treasures. Interestingly it contains the largest known white dwarf at it’s centre.
Brocchis cluster is a chance grouping of stars that form one of those surprising and unnatural asterisms, in this case the shape of a coat hanger. It can be seen in the centre of the summer triangle with the naked eye as an unresolved patch of light, often glimpsed with averted vision. Looking through binoculars or a telescope will reveal the coat hanger arrangement.
There are a range of clusters in this part of the sky and a couple that are definitely worth tracking down. NGC6834 is an open cluster of mag 7.8 And have a look at star 20 vulpeculae. Next to it are clusters NGC 6882 and 6885. But this is a bone of contention amongst astronomers and a possible error in the NGC. Most claim to be able to only see one cluster… So happy hunting and I wish you clear skies.
End of podcast:
365 Days of Astronomy
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