Podcaster: Ralph & Paul
Title : Awesome Astronomy’s October Sky Guide
Organization: Awesome Astronomy
Link : www.awesomeastronomy.com
Description: What to look out, and up, for in October.
This month we take a look at the constellation of Perseus the Hero for the beginners guide – we begin with the Alpha Persei Cluster around bright star Mirfak, swing by Algol, the Demon Star, and finish up with the Double Cluster – arguably the finest cluster (or clusters) in the Northern Hemisphere.
Next we round up the planets that are visible in October: Uranus & Neptune are still hanging on while Mars, Jupiter and Venus combine to make some stunning planetary conjunctions most of the month. We bring you the month’s moon phases and two meteor showers – the Draconids and the Orionids. Then, for our deep sky challenge, we take a look at one of the finest globular clusters in the northern hemisphere, a galaxy that’s thought to be a mirror image of our own Milky Way, a grouping of five galaxies and the brightest galaxy of them all, Andromeda, as we tour the adjacent constellations of Andromeda & Pegasus.
For those in the Southern Hemisphere, 365 Days of Astronomy also play Alice Enevoldsen’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
Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by — no one. We still need sponsors for many days in 2015, so please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at signup@365daysofastronomy.org.
Transcript:
Paul: Well here we are in October again, you’ve dug out the coat you threw in the cupboard 6 months ago and your trusty flask is once more seeing the starlight. The nights are definitely longer than the day and you can get in a decent couple of hours observing before the ten o’clock news. Old favourites are back in the sky, over to the west summer is still hanging around in the form of the infamous triangle, looking south the great square of pegasus dominates all and a glance to the east will see the first of those winter favourites creeping over the horizon, yep that is the Pleiades you can see sitting on the horizon not long after sunset, the sky seems lacking in brilliant constellations this month but there is still plenty to see. But before we look at those Ralph take us through your beginners guide.
Ralph: Okay, so for the beginners and young astronomers this month, we’re going to take a look at Perseus the constellation named for the Greek hero beheader of the Gorgon Medusa and saviour of Andromeda from the sea serpent Cetus.
Not surprising that it sits just to the left of Andromeda, Perseus is best found by looking for the brightest star low in the north west, Capella. An outstretched hand’s width above and to the right of Capella is the magnitude 1.7 yellow/white star Mirfak that sits in the middle of this upside down Y-shaped constellation just below the W-shaped constellation of Cassiopeia. And we’ll start with this region around Mirfak, also known as Alpha Persei. Mirfak is the starting point for locating the cluster known as Collinder 39, Merlotte 20 or the Alpha Persei Cluster because Mirfak sits right in among it. Sitting 600 light years away from us this collection is perfect to scan with a small telescope or binoculars as it spans 6 full moon widths and contains loads of coincidental patterns of star clusters within it – all around 60 million years old.
Next up is a star that featured in Paul’s 5 minute concept on Cepheid variables last September, Algol, the Demon Star. Look for the star an outstretched fist width to the right of Mirfak – they should look almost the same brightness. Except every 2 days and 21 hours, Algol dims from magnitude 2.1 to 3.4, going from the 2nd brightest star in the constellation to the 8th before returning to its former glory after 10 hours in the shade of a dimmer companion star that passes in front of it. You can easily tell the difference in brightness with the naked eye but nothing’s better than a telescope to bring it closer to home.
Heading away from the brighter stars in Perseus we swing over to the area of sky that sits exactly halfway between Mirfak in Perseus and the middle star in the W-shape of Cassiopeia. In dark skies, you should see a smudge of light here with the naked eye and this is perhaps the most visited open cluster of them all. While it lacks the sheer brilliance of the Pleiades cluster in our winter skies the Double Cluster eclipses by being… well, a two for one. NGC869 and NGC884 sit as two separate open clusters less than half a degree apart in the sky and can be easily, and properly, viewed together in the field of view of the same eyepiece. In dark skies these clusters blaze away like jewels against the black background and choosing the right magnification reveals stars in the centre of NGC 869 in the formation of a sword handle – the handle of Perseus’ sword.
Paul: Okay, time to take in what the solar system has on offer this month and we start with an opposition.
Uranus has been gracing our sky for a while now and over the summer reached naked eye visibility for those with a good sky. On october 12th the planet reaches opposition and is at it’s closest to Earth for the year. The 7th Planet is in Pisces and will be magnitude 5.7, faint but most should pick it up in a clear sky and certainly in a pair of binoculars or a small scope. There isn’t much to see unless you have a large telescope and hunting the moons usually requires imaging. It is still worth taking a look at george’s star and remember this was the planet discovered by an amatuer in his backgarden using a 7” scope.
he planetary highlight through october is the triple conjunction of Venus, Jupiter and Mars. Now this will be the gift that keeps on giving all month and on into November with all three planets close together on any day you choose. If you are up early before dawn, 4-4.30 am being a good time to be in position then in the east you will see venus, Mars and jupiter making a triangle near the horizon which on the first is about 16 deg across, pretty close on any normal year, but keep watching through the month and the middle of the month around the 13th you will see mars and jupiter 21 arc minutes apart with venus just 6 degs away above them. By the 23rd the three planets are at their closest as a triple conjunction forming a neat triangle. By the 25th it’s venus and jupiter getting cozy being just a smidge over a degree apart, almost a repeat performance of the summer evening conjunction earlier this year. They grow further apart as the days go on but this will still be a stunning sight well into November.
As an added challenge for the very observant around the middle of the month you will also see mercury just before dawn about 20 degs below the conjunction, so if you are lucky you can see all of our nearest planets in the same patch of sky. For added beauty watch the conjunction around the 8 9 10 for the appearance of the moon, surely one of the best planetary photography chances of the year.
The moon this month starts just past the full moon that gave us the total lunar eclipse at the end of September, reaching last quarter on the 4th. We can enjoy dark skies through the middle of the month as we hit new moon on the 13th, we get back to first quarter on the 20th and hit full moon on the 27th.
There are two meteor showers of note this month, the first is the Draconids which peaks on the night of the 8th, which many of you will have immediately realised is the night of the full moon. It’s a smaller shower at the best of times so this year will be a difficult to see. The far more impressive Orionids will be peaking on the night of the 22nd/23rd. This shower is the debris trail of Comet Halley and with the moon at it’s new phase this has potential for a good shower. The best time to observe is after midnight and the radiant is in orion.
This month for our deep sky challenge we will be looking at the constellations Pegasus and Andromeda, which many feel are essentially the one large constellation anyway and indeed they share some stars. This month the square of pegasus will be one of the dominant features high in the sky looking south with the upside down head of the horse and it’s front leg off to the left while it’s body morphs into the daughter of cepheus and cassiopeia chained to the rock awaiting her fate at the hands of Cetus.
We start in Pegasus with a relatively easy messier in the form of M15, a bright globular cluster not far from the ponies nose star Enif. Magnitude 6.4, it is 34,000 light years away and has a rich bright centre. NGC7331 is a must for galaxy enthusiasts, a william herschel discovery you are looking at a galaxy often referred to as the Milky Ways twin. It is magnitude 9.5 and is found in the northern part of pegasus, the nearest bright star being eta pegasi. The real challenge out there is a Stephen’s Quintet. Visually a dark sky and a medium to large scope is needed and imagers will need patience. This is a tight grouping of 5 galaxies, the brightest NGC7320 is not actually part of the group and is a chance alignment but will probably be the galaxy you find first. It is believed that the other four are in the process of forming a single galaxy. The good news is that if you have found NGC7331 then Stepehn’s Quintet is about half a degree away towards star 38 pegasi.
In Andromeda we have the famous M31 galaxy but this tends to be the object everyone looks at in Andromeda so for this month I am going to point you at three other objects. The first is open cluster NGC752. This is below the star Almaak and is a caroline Herschel discovery. in a good sky it is just naked eye visible as a hazy unresolved patch and binoculars or a small scope will reveal around 60 stars. At the other end of the constellation in a patch of sky away from the main body is planetary nebula NGC7662 or the blue snowball nebula. Now this is one of my favourite objects and is indeed a pleasing blue colour, magnitude 9.4 and not always easy to locate but well worth the hunt. The last object this month is the seasonally appropriate Mirach’s Ghost. Take a look at the bright star Mirach or beta andromedae and then look 7 arc seconds away and look for a faint companion that because of the brightness of the nearby star seems to dip in and out of sight. This is NGC404 a lenticular galaxy 10 million light years away and just outside our own local group.
So all that remains is to wish you clear skies and happy hunting.
End of podcast:
365 Days of Astronomy
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