Podcaster: Ralph & Paul
Title : Awesome Astronomy’s July 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.
Join Ralph & Paul at the beginning of each month, for an informative and fun astronomy programme 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 and listeners’ astronomy questions answered.
As both presenters have been accused of being a little skeptical in the past, you can also expect everything to be frivolous but fact-based
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Paul: July. Long warm days, the buzz of insects in the garden, the smell of bbqs on the breeze, shopping centres filling with children on their summer breaks and while not the best time of year for dark sky astronomy in northern latitudes there are some real gems to look for and it is a great time to spend some time with the most familiar star in the sky, our own Sun. We have a nice meteor shower to look out for and of course the ever present moon provides us with a few opportunities. But first Ralph is going to talk you through our beginners guide.
Ralph: This month for the beginners we’ve got a real treat of the summer skies in Cygnus the swan. If you look east as soon as it’s dark you’ll easily make out the Summer Triangle of stars – they’re the three brightest stars in that section of sky, each about an outstretched hand’s width apart.
The star that’s furthest left is Deneb – a hot giant star 2 and a half thousand light years away and more than 100,000 times more luminous than our sun. Deneb forms the tail of the swan and if we look right, towards the next bright star in cygnus, Sadr, this forms the crossover point where the beak of the bird, Albireo, sits even further to the right and the wings of the swan can be seen stretching out above and below that central star Sadr. So it’s easy to see why Cygnus is often referred to as the Summer Cross.
It’s also a large constellation in its own right that sits in a very dense starfield because this point in the sky is where the Milky Way – the band of billions of stars that make up the plane or disk of our spiral arm galaxy are most concentrated to northern hemisphere observers. And not only are there countless stars to scan for clusters, but there’s also a band of thick dust clouds that you can see with the naked eye as a dark dust lane running through the seam of the milky way. Because of this Cygnus Rift, as it’s sometimes called, there are also plenty of nebulae, or glowing gas clouds, to be found in Cygnus too. Unfortunately, though large and stunning in photographic images, Cygnus’ nebulae are often difficult to pick out through the eyepiece without the use of nebula enhancing filters unless you have super dark skies.
But the first object to try and find can be seen with the naked eye. If you have very dark skies, look at the area around Deneb and you should see a fuzzy, slightly brighter patch of sky a couple of outstretched fingers width below Deneb. This is averted vision at work, where you use the more receptive parts of your retina to pick out fainter objects. If you have found it, you’ll know because it’s a monster around 4 times the width of the full moon! If you want to try with a scope, use a very low power eyepiece and an Oiii filter may help.
Next up’s a nice open star cluster from Charles Messier’s catalogue, M29. Go back to the central star in the summer cross, Sadr, and trace a line south to the next bright star Gienah [Jee-nah]. About 1 outstretched finger’s width south of Sadr along that line and just to the right of that point is the two opposite facing semi circles of stars that make M29 look like it’s nickname, the Cooling Towers. At magnitude 6.6, these are bright enough to be seen in binoculars or a scope in any skies but, as always, darker skies will be more rewarding as the greater contrast will make the stars all the more jewel-like.
Finally, we have the real treat in Cygnus that anyone can find and can be seen no matter how soupy and light polluted your skies may be. So this is a must-see for city astronomers. From Deneb, scan right through Sadr and the next bright star along that line in the chest of the bird to the swan’s beak, also known as Albireo. With just moderate magnification, or a pair of 20×80 binoculars, Albireo will split into what’s undoubtedly the most beautiful pairing of fine blue and rich yellow components. It’s now thought that these two stars aren’t actually orbiting one another but this chance alignment of stars 430 light years away are another one of those ‘wow’ objects that you’ll keep going back time and time again.
Paul: We should begin the solar system round up by mentioning that despite this being the northern hemisphere summer July 4th is the point where Earth reaches reaches aphelion,and will be 152,098,232 kilometres from the Sun, the furthest the two bodies get annually
Starting with the planets, Mercury is a difficult predawn target towards the end of the month. It will get quite bright at magnitude -1.27 but it is fighting the dawn and you will need to be quick.Maximum elongation is on the 12th but you may find the days after easier.
Venus is still in the dawn sky and is on the move from taurus into gemini which of course means it is moving towards the sun. Magnitude -3.3 it will be visible but not in a dark sky and there will not be a chance for long lingering views.
Mars is 86% illuminated and magnitude 0.4. It will be sitting low in the evening sky near Spica in Virgo. It is getting much smaller than in the spring and while worth a look, especially if you have a larger scope, it is well past it’s best for this apparition.
Saturn is not far behind mars in Libra and is low in the evening sky, opposition was at the start of May and like mars it is now getting far past it’s best, but as ever the ring world is always worth a look. It will be fading in brightness and will be 0.65 by the middle of july.
Uranus and Neptune are beginning to make their presence felt in the sky as summer goes on. Neptune rises first in Aquarius after ten thirty and can be seen as a small blush disc of around magnitude 7.6. Worth a look and perfectly possible in binoculars. Uranus rises after midnight in picses and is already mag 6.15, putting into naked eye range for the keen of sight. A bluish green disc and very small, large scopes may tease out a little more but really both these planets are about the pleasure and knowledge that you have been observing such distant planets.
Jupiter isn’t visble this month.
Moving on to our nearest neighbour the moon. June brought new moon on the 27th so July starts with a thin cresecent moon that moves to first quarter on 5th at 11.59UT. Full moon is reached on 12th at 11.25UT. Last quarter is reached on 19th at 2.08UT and we get back to dark skies in the last part of the month as new moon is on the 26th at 22.42UT. The furthest apogee of the year occurs on the 28th with the Moon 406,568 kilometres away at 3:28 UT.
The moon has some nice encounters this month with Mars nearby on the 5th, Saturn on the 7th, Neptune 15th and Uranus on 18th.
The beginning of the month is also the time for minor bodies. Pluto reaches opposition on the 4th in the constellation of while Ceres and Vesta will be a mere 10 arcminutes apart in Virgo. Now this will be a very difficult event to view given the time of year and the altitude of virgo, but more southerly observers may want to give it a shot.
The night of the 28th-29th sees the peak of the Delta Aquarids which are produced by comets marsden and Kracht. ZHR is around 20 and with the moon new on the 26th this will be a good year to observe this shower.
This months deep sky challenge turns our attention to a constellation that is only to be seen in the north during the summer months and is really a globular cluster hunt – Ophichus. You will find it below Hercules and to the right of the summer triangle it is home to a fantastic set of globular clusters, M10 and M12 can be seen in the same wide angle and picked up in binoculars. M10 is 14,300 light years away and is 83 light year across while M12 is more distant at 15,700 light years and slightly smaller at 75 light years a cross. Other globulars to be hunted down are M9 which is one of the closest to the galactic centre, the 30,000 light year distant M14, the oblate looking M19 and the loose globular cluster M107. Ophichus also contains the a spectacular imaging target in the Rho Ophiuchi complex, a beautiful patch of nebulosity on the southern edge of the constellation near the star Antares.
That is the end of this months guide and all that remains to say is clear skies and happy hunting
End of podcast:
365 Days of Astronomy
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