Podcaster: Ralph & Paul
Title : Awesome Astronomy’s August Sky Guide
Organization: Awesome Astronomy
Link : www.awesomeastronomy.com
Description: What to look out, and up, for in July. We start with the beautiful summer constellation of Cygnus in our beginners’ and young observers’ guide. Next up is Mercury, Venus, Mars & Saturn and some lovely lunar conjunctions to enjoy this Month. The Delta Aquariid meteor shower makes an announcement before we round up the best of July’s deep sky offerings in the constellation Ophiuchus Bio: Awesome Astronomy is the show for anyone and everyone who has even the slightest interest in astronomy and science.
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: August. While others start to frown a little as the nights start to draw in, lengthen and get darker, astronomers begin to quietly celebrate as the new season of night time observations and hours of faint fuzzies is almost upon us. It’s a month often overlooked in astronomy, many out there will be eyeing September and dreaming of early autumn, but August is a month of darkening skies, warm evenings, spectacular sights and of course that meteor shower. So kick back and let us guide you through the end of summer, first up being our beginners guide and Ralph has something a little more challenging but well worth the time.
Ralph: Thanks Paul, for the beginners and young astronomers this month we’re going to look at a constellation that’s a bit trickier than usual and one that, for that reason, often gets overlooked: Cepheus the King.
Overlooked, perhaps also, because it doesn’t contain any nice bright Messier objects and doesn’t stand out as a bright shape in the way Ursa Major or Cygnus do. It does have a nice simple house-shape to help you locate it though.
If you can wait until around 1am this month, it should be directly overhead. It also sits directly above the W-shape of Cassiopeia. You should see a faint square of stars, with Alderamin being the brightest of the quartet, and another star, called Errai, forming an apex on the house-shaped constellation.
While not easy to pick out compared to many of the other glowing constellations at this time of year, Cepheus has historical significance, because it gave its name to a type of star that pulsates with a predictable brightness that allows us to accurately judge distances across the galaxy and to other galaxies as well. A study of the star Delta Cephei in 1784 by John Goodricke gave the name Cepheid Variables to these kind of stars. So we’ll start the beginner’s guide by pointing the way to the star that became our original galactic tape measure.
Find the W shape of bright stars in Cassiopeia and draw a line from the middle star in the W all the way to bright star Vega. Exactly half way along that line is a white magnitude 4 star just to the left of the bottom of the house shape. That’s our cosmic yard stick, Delta Cephei.
Next we’re looking for a star of similar brightness. Find the 2 stars that form the base of the house shape, Alderamin and zeta Cephei. About an outstretched finger’s width, just below the half way point sits mu Cephei. This is a monster star, so large that it’s radius would swallow up Jupiter if it were in our solar system. One of the largest stars in the entire galaxy, a telescope will show this as very red, hence the name it gained after William Herschel’s observations, Herschel’s Garnet Star.
Finally, move down the same distance from the Garnet Star – about an outstretched finger’s width – and you’ll find a rather loose cluster of stars, if you have dark skies or an Oiii filter you might pick out a smudge of nebulosity in this star forming region of illuminated gas called ic1396. If you can take a long exposure camera image in dark skies, you’ll reveal this to be the beautiful Elephant Trunk Nebula.
Paul: Ok so on to our Solar System guide for the month.
Planets are thin on the ground in August and those all nighters with Jupiter high up in the sky are now definitely a distant winter memory. All the Planets except Mercury are visible but the by the quirks of orbital mechanics the brighter and more visible planets, Venus, Mars,Jupiter and Saturn are all in the other half of the solar system and appear to be clinging closely to the Sun.
Mars and Saturn are our evening pairing in August and appear at dusk in the southwest. Mars closer to the sunset and saturn nearer to the south. Both are low down and magnitudes are falling as we draw further away from both planets. The two planets will appear to approach each other through august as they have been doing in July and by the second half of the month they will essentially be in conjunction, the few days either side of 26th will see them at their closest, with mars passing below saturn in Libra.
For the early risers we have the dream team of bright planets moving into conjunction, Jupiter and Venus. Venus has been the morning star for many months now and is still blazing away before sunrise, but now Jupiter is joining the view after its trip behind the sun and is beginning its 2014/15 apparition with a spectacular show. August 18th will be the morning to get up early and is certainly not a sight to miss with Jupiter and Venus just quarter of a degree apart and visible in the same eyepiece. You will have Jupiter at Mag -1.7 and the galilean moons parked behind a -3.8 Venus which will be 95% illuminated. If that wasnt enough, they will be parked on the edge of M44 the Beehive cluster. Set your alarms, and be in position for about 3.15 UT if you are at latitude 51, find yourself a hill with a good eastern view for the longest views.
The icy planets are on the same side of the Sun as Earth this month with Neptune hitting opposition on 29th August in the constellation of Aquarius. Definitely a telescope or large binocular target even at it’s closest and the best magnitude we can expect is 7.8. Not much to see even in quite large scopes, but don’t let this put you off, here is the most distant planet you can see. Uranus is in Pisces and is contrast to Neptune a far more visible prospect sitting on the edge of naked eye visibility for those with sharp eyes and good skies. It doesn’t hit opposition until October so we have some good viewing time ahead of us in darkening skies and those with imaging kit and large scopes might try to track down those elusive moons.
The Moon begins the month just past new and reaches first quarter on the 4th at 00.49 UT. By the 10th we reach full moon at 18.09 UT and then move on to last quarter on the 17th at 12.26 UT with dark skies returning by the end of the month when we reach new moon at 14.31 UT on the 25th.
The best of the moons encounters this month are with the planets. The 3rd of August sees the moon sitting between Mars and Saturn in the evening sky as the two planets approach conjunction. Then for the early risers who aren’t too tired from taking in the Jupiter Venus conjunction on the 18th then set your alarms again for 5 days later on the morning of the 23rd when the two planets will be a little further apart but joined by the late crescent moon, surely the potential for one of the most beautiful celestial sights this summer.
We can’t leave the solar system round up without mention of that meteor shower. I am of course talking about the perseids which last year put on a spectacular show. This year the peak of the shower, which is on the night of the 12th-13th falls just 2 nights after full moon so this year is not going to be a vintage shower and only the brightest meteors will shine through the moon glow. The radiant is in Perseus and you should be able to lay back and look at any patch of sky and enjoy the show. For northern observers it is well worth having ago as despite the moon this is the one really decent shower that comes at a warm comfortable time of year.
Now for our deep sky challenge this month we are moving into the constellation Aquarius, where you will currently find the planet Neptune. Aquarius is a rather indistinct constellation with no star above magnitude 2. It’d best found by looking for pegasus and the circlet of pisces below and then turning to the area of sky below and to the right.
Now Aquarius may be lacking in bright stars but it makes up for this with some fantastic deep sky objects and this month we have three messier objects, three planetary nebulae and a galaxy for you to hunt down.
The easiest of the objects to locate are the three messiers, M2 and 72 are both globular clusters while M73 is probably best described as a mistake. M2 is a bright rich glob that can be found 5 degrees north of star beta aquarii. With a magnitude of 6.3 it is naked eye visible in a good sky and is one of the largest globs at 175 light years across. M72 is a less dense and far more distant cluster, at almost twice the distance from us as M2. Magnitude 9.3 it needs larger apertures to tease out the individual stars.It is found below star epsilon aquarii.
Very close to M72 is M73, included by Messier and described as a cluster of four stars with some nebulosity. Nobody has ever seen the nebulosity since and centuries of debate was resolved recently when it was shown that the stars of M73 were in fact an unrelated asterism. Still an interesting object if only for the curiosity value.
Our planetary nebulae are all some of the finest examples of the type you can hunt down, NGC6781 is magnitude 11 copy of the ring nebula, set in a dense star field and making a perfect smoke ring in the eyepiece.
NGC7293 or the Helix Nebula is the closest planetary nebula to earth, somewhere between 650-700 light years away. This also makes it the largest but because of this it has a low apparent surface brightness and while nominally magnitude 7.3 the Helix is a difficult and faint challenge.
NGC7009 is the Saturn nebula, a planetary 3000 light years away that appears to have two small protrusions each side giving it the appearance of saturn in a small scope.
Last in our deep sky challenge is galaxy NGC7727, a peculiar galaxy visible in amatuer scopes that is probably the result of galactic collision and in the process of becoming an elliptical galaxy. A decent scope and a dark sky should reveal two cores and large scopes will see the spiral arms.
Well that is all from this months sky guide and it only remains for me to wish you clear skies and happy hunting.
End of podcast:
365 Days of Astronomy
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