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Urban observing July 2014 July 2, 2014

Posted by aquillam in Astronomy, Urban Observing.
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I guess time flies when you’re having fun, because the start of July really snuck up on me.

Special Events

Aphelion occurs on July 3. This is the day when the Earth is farthest from the Sun. Clearly, our distance from the Sun is not related to the temperature outside here in the northern hemisphere!

Meteor Showers

July and August bring some of the best meteor showers of the year. The July ones in particular tend to have prolonged peaks, so there are many good nights for watching meteor showers. The June Bootids are winding down as the month begins. A weak shower, this one is primarily worth watching because the radiant is near zenith at 1 AM, which is not only a good position, it’s also after Moonset, which eliminates at least one big source of light pollution. Mid July brings the Alpha Capricornids, active July 11 – August 10. The peak will be the night of July 29, but it’s a wide peak, so a night or two on either side should be good too, a timeframe that happens to coincide with the new moon and the next few nights. Although it typically only produces about 5 meteors an hour, a relatively high number of fireballs makes it worth watching anyway, even from poor urban skies. The Delta Aquariids are active from July 21st to August 23rd with the peak on July 28. This is a strong shower with a rate of around 16 meteors per hour, but often fairly dim meteors with few fireballs. However, it is one of the best showers for observers in the tropics.

Locations of the radiants of the Alpha Capricornids and  Delta Aquariids.

Locations of the radiants of the Alpha Capricornids and Delta Aquariids on July 28 at 2 AM. Image made with Starry Night.

Moon

The full moon is July 12 at 7:25 UT. That’s 3:25 AM local time Ann Arbor. New Moon falls on the 26th, so the end of the month is your best chance for deep sky observing.

Planets

Mercury returns to the morning sky at the opening of the month. It reaches greatest Westward elongation on the 13th. It is at it’s closest to Venus on the 16th, and they make a rather nice pair in the predawn sky.

Venus is in the middle of the image, Mercury about half way beteen Venus and the horizon. The first rays of dawn appear to the left of Mercury.

Looking ENE half an hour before dawn on July 16. Image made with Starry Night.

Venus is still slowly making its way towards superior conjunction. It starts the month close to the red giant Aldebaran. Look for it among the stars of Gemini’s feet along with a very old moon, Mercury, and a rising Orion on July 24 at 5:30 in the morning in Ann Arbor.

A very thin crescent moon is next to Venus, which is above Mercury.

Venus, Mercury, and a very old moon about 45 minutes before sunrise on July 24. Image made with Starry Night.

Mars and the star Spica make a striking pair in the evening skies this month. They’re at their closest to each other on July 13. On July 5, the first quarter Moon will pass less than a degree from Mars, making it possible to get both into the field of view of a small telescope.

Mars and the Moon are practically on top of each other.

Looking SSW at 10 PM on July 5. Mars and the Moon are in conjunction. Image made using Starry Night.

Jupiter is basically lost in the glare of the sun this month. Conjunction occurs on the 24th, so look for it to reappear in the morning skies in August.

Saturn is the gem of the evening skies this month. Look southward at 10 PM all month to find it. On July 7, a fat first quarter moon passes less than half a degree from Saturn.

Saturn and the Moon are practically on top of each other.

Looking SSW at 10 PM on July 7. Saturn and the Moon are in very close conjunction.

Deep sky objects

As the nights lengthen, it becomes reasonable to look for deep sky objects at 10 or 11 PM again. M13, the great cluster in Hercules is one of the nicest globular clusters in the sky. It’s also relatively easy to find, being not far from one of the stars in the Keystone. Not far away are two more nice globular clusters, M3 and M92.

Several consellations and some of the brighter deep sky objects are marked

Looking toward zenith while facing south (ie north is at the top, east is to the left.) Click for a larger version. Image made using Starry Night.

You can’t beat summer nights for planetary nebulae. M57 is one of the higher surface brightness nebulae, and is relatively easy to find, being located between two stars in Lyrae. An OII or nebula filter can make this pop out of even some pretty bad city skies. Nearby, if you have darker skies, you’ll be able to see the larger but lower surface brightness dumbbell nebula. It’s a tough catch from Ann Arbor, but not completely impossible.

If you’re a fan of open star clusters, two of the nicest, the butterfly cluster (M6) and Ptolemy’s cluster (M7), finally make it above the horizon at a reasonable time in the end of July. Not far from the double star Shaula in the tail of Scorpius, these can be a bit tough to spot in light polluted skies, but if you can get them in your telescope, they’re well worth it.

Sagittarius, Scorpius, and several star clusters are marked.

Looking south on July 22nd at 11 PM. Image made with Starry Night.

 

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