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THE NIGHT SKY FOR AUGUST 2014

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during August 2014.

High in the south in the evening is the Summer Triangle of Deneb in Cygnus, Vega in Lyra and Altair in Aquila, with the four brightest stars in Cygnus forming the asterism of the Northern Cross. The small constellation of Delphinus the Dolphin lies below Cygnus. The Great Square of Pegasus is rising in the east, and its top-left star, Alpheratz, can be used to locate the Andromeda Galaxy. Starting there, move left to the next bright star, curve up and right to another, go sharp right one more star, then move the same distance again to find our nearest neighbouring large galaxy, once known as the Great Nebula in Andromeda. Cassiopeia is high in the north, above Perseus and its bright star Mirfak, with the Perseus Double Cluster between the two constellations.

The Planets

  • Jupiter reached superior conjunction (behind the Sun in the sky) on the 24th of July, so it only becomes visible in the middle of August, low in the east-north-east before dawn and shining at magnitude -1.8. By month's end, it is 20 degrees above the horizon at 05:30 BST (British Summer Time, 1 hour ahead of Universal Time). With a disc 32" across, a small telescope can be used to observe the equatorial belts and the accompanying Galilean moons. Jupiter lies within 4 degrees of Venus from the 14th to the 21st.
  • Saturn is in Libra, near the double star Alpha Librae. Its brightness declines from magnitude +0.5 to +0.6 during the month. It is 20 degrees above the horizon at sunset, and a telescope reveals its 17" disc, ring system and largest moon, Titan.
  • Mercury is so low above the horizon at nightfall that it is very difficult to spot this month.
  • Mars begins August between the stars Spica and Alpha Librae, and moves from Virgo into Libra on the 10th. Its apparent size shrinks from 7.7 to 7" during the month, while it dims from magnitude +0.4 to +0.6. Its low elevation as darkness falls makes it difficult to observe surface details through a telescope, due to atmospheric scintillation.
  • Venus rises in the east-north-east before dawn, reaching 20 degrees above the horizon by sunrise on the 1st. Its angular size drops from 10.7 to 10.2" over the course of the month, but its percentage illumination increases from 82 to 97 percent as it moves towards the far side of the Sun from our perspective, so its brightness remains at magnitude -3.8 all month. Venus moves from Gemini into Cancer on the 11th, and then into Leo on the 27th, by which time it is only 14 degrees above the horizon at sunrise.

Highlights

  • You can use binoculars or a telescope to observe the globular cluster M13 and the Double Double this month. The former is a lovely group of stars in Hercules, the latter is a pair of double stars in Lyra.
  • Neptune can be found using binoculars or a small telescope this month. It is at opposition (opposite the Sun in the sky and near its closest approach to Earth) on the 29th and has a magnitude of +7.9, lying in Aquarius and reaching a maximum elevation of 27 degrees around 01:00 BST. A telescope of 8 inches or more in aperture may reveal Neptune's largest moon, Triton.
  • The Moon, Mars and Saturn are close together in the sky an hour after sunset on the 3rd, low in the south-south-west after sunset.
  • The Moon makes a close approach to the Earth just as it becomes full at around 19:00 BST on the 10th. It rises at 20:15 BST, and is about as large in angular size as it ever appears on Earth, leading to the name of 'megamoon'.
  • The annual Perseid meteor shower reaches its maximum this month, although the nearly-full Moon hampers viewing. Rising in the north-east, its radiant in Perseus is highest in the east and most active before dawn on the 12th and 13th as the Earth passes through the debris of Comet Tempel-Tuttle.
  • Venus and Jupiter are just 12' apart in the east-north-east just before dawn on the 18th, and the open cluster M44 - also known as the Beehive Cluster or Praesepe - is just a couple of degrees away from them. You need a low horizon to see them, as they are just 5 degrees above the horizon at 05:00 BST.
  • Venus, Jupiter and a waning crescent Moon appear together an hour before sunrise on the 23rd, but require a low eastern horizon to be visible.
  • A lunar feature known as the Straight Wall can be seen well using a telescope on the 4th and 17th, as the terminator is close to it, casting a long shadow. It is actually more of a gentle escarpment than a straight wall.

Ian Morison's new book, An Amateur's Guide to Observing and Imaging the Heavens, is out now.

Southern Hemisphere

Claire Bretherton from the Carter Observatory in New Zealand speaks about the southern hemisphere night sky during August 2014.

This month sees Scorpius and Sagittarius high overhead in the evening sky. Scorpius, a winter constellation, is easy to spot by its orange star Antares, which lies just east of the zenith. A curve of bright stars stretches out towards the right, forming his tail. Antares is a red supergiant star with a radius more than 800 times that of the Sun. To Maori, this group of stars is known as Te Matau a Maui: the fish-hook of Maui. Maui used this hook to pull a great fish out of the ocean which became the north island of New Zealand: Te Ika-a-Maui. The red star is known as Rehua, and represents a drop of blood that Maui took from his nose to use as bait. Below Scorpius is an upside-down teapot shape formed from the brightest stars in Sagittarius. The broadest and brightest part of the Milky Way lies towards Scorpius and Sagittarius, high in our eastern evening sky.

The centre of the Milky Way provides a whole assortment of stunning nebulae and star clusters to observe. Lying along the tail of the Scorpion is NGC 6231, a bright cluster of stars which looks like a small comet. Estimated to be only 3.2 million years old and nearly 6,000 light-years away, if the cluster were placed at the same distance as the Pleiades then some of its stars would be amongst the brightest in the night time sky. About halfway between the Scorpion's sting and the spout of the Teapot is M7. This is an open cluster of stars easily visible to the naked eye, and a lovely sight through a good pair of binoculars. Nearby and somewhat fainter, M6, the Butterfly cluster, is also well worth a look in binoculars. To the left of the Teapot's spout, and just about visible to the naked eye, is the Lagoon Nebula, or M8. This is a huge cloud of interstellar gas and dust where new stars are being formed, and where their ultraviolet radiation causes leftover hydrogen gas to glow. Along with the nearby Trifid Nebula (M20), the Lagoon Nebula is a good target for binoculars or a small telescope. The Trifid nebula combines emission and reflection nebulae with an open cluster of stars. This part of the sky also contains a number of globular clusters, each hosting hundreds of thousands of ancient stars that date back more than 12 billion years. Over 150 globular clusters are found in the halo of the Milky Way, and their distribution provided early evidence of the scale of the Milky Way and our position within it. The brightest globular cluster is M4, and this is also one of the easiest to find as it lies just 1.3 degrees west of Antares. Appearing as a small fuzzy ball in binoculars and small telescope, a slightly larger telescope will begin to pick out individual stars. Also in this region, near the top of the Teapot, is M22, one of the closest globular clusters to us at distance of around 10,000 light-years.

From its bright centre in Sagittarius, the Milky Way stretches out from east to west in the early evening. Along its path are found the majority of the bright stars in our night-time sky. In the north, just to the left of the Milky Way, is the bright star Vega, which forms part of the constellation of Lyra the Lyre. Opposite, in the southern sky, the second brightest night-time star, Canopus, can be found in the constellation of Carina. To Maori in Aotearoa (New Zealand), this star is Atutahi or Ao-tahi, which means 'to stand alone'. Running back along the Milky Way towards Scorpius, we pass the False and Diamond Crosses before arriving at Crux, the Southern Cross. The smallest of the 88 official constellations, it has the appearance of a diamond shape of four bright stars along with a fifth fainter star. It is known to Maori as Te Punga, the anchor of Tama-reriti's Waka. Alpha Crucis appears to the unaided eye as a single star of magnitude 0.9, but small telescopes reveal it to be a double star with blue-white components of magnitudes 1.4 and 1.9. Nearby is NGC 4755, an open cluster of stars also known the Jewel Box. It is rich and bright with stars, showing delicate colours accentuated by an orange-red supergiant. It can easily be seen with the naked eye, but binoculars and telescopes reveal much more detail. Just to one side is a dark patch known as the Coalsack Nebula. This is a cloud of interstellar dust and gas that obscures the light from more distant stars, appearing as a darkened area against the bright backdrop of the Milky Way. To Maori it is known as Te Patiki or the Flounder. East of Crux are the two bright pointer stars, Alpha and Beta Centauri, marking the front hooves of Centaurus the Centaur. The brightness and number of stars rapidly drops off when we look away from the path of the Milky Way, and after sunset the constellations of Virgo and Corvus can be seen to its west.

The Planets

  • Mars and Saturn sit near to Spica, the brightest star in Virgo, with the orange star Arcturus below. Mars and Arcturus have red hues, while Spica is a brilliant blue-white and Saturn is yellow. Mars and Saturn are at their closest on the 25th. Small telescopes reveal the Saturn's rings and its largest moon, Titan, looking like a small star around four ring diameters away from the planet. More powerful telescopes should reveal faint banding in the Saturn's atmosphere, along with gaps and colour variation in the rings, as well a number of smaller moons. Mars appears as a small, red disc, and is getting fainter as we move away from it on our faster inner orbit.
  • Also in the western sky is the planet Mercury, climbing higher as the month progresses and setting 1.5 hours after the Sun by month's end. It is close to the crescent Moon the 27th.
  • Brilliant Venus and Jupiter appear in the morning sky and are at their closest on the 18th, when there will be less than the diameter of the full Moon between them.
Compiled by Ian Morison


Night Sky Note for July 30, 2014

Wednesday, July 30, 2014
The Abrams Planetarium Night Sky Notes has been discontinued. Please find Abrams Planetarium on Facebook and Twitter. Also look at the Abrams Planetarium Sky Calendar for astronomical information. Visit abramsplanetarium.org for more information.

Night Sky Note for July 22, 2014

Tuesday, July 22, 2014
The waning crescent Moon is near Aldebaran. Look east two hours before sunrise.

Night Sky Note for July 21, 2014

Monday, July 21, 2014
The waning crescent Moon is near the Pleiades star cluster. Look east two hours before sunrise.

Night Sky Note for July 20, 2014

Sunday, July 20, 2014
Mars is 3.6 degrees to the upper left of Spica.

Night Sky Note for July 19, 2014

Saturday, July 19, 2014
The Last Quarter Moon is in the southeast an hour before sunrise.

Night Sky Note for July 18, 2014

Friday, July 18, 2014
Mercury is 6.3 degrees to the lower left of Venus. Look ENE 45 minutes before sunrise.

Night Sky Note for July 17, 2014

Thursday, July 17, 2014
Mars is 2.3 degrees to the upper left of Spica.

Night Sky Note for July 16, 2014

Wednesday, July 16, 2014
Mercury is 6.2 degrees (minimum distance) to the lower left of Venus. Look ENE 45 minutes before sunrise.

Night Sky Note for July 15, 2014

Tuesday, July 15, 2014
Mars is 1.6 degrees to the upper left of Spica.

Night Sky Note for July 14, 2014

Monday, July 14, 2014
Mars is 1.4 degrees to the upper left of Spica.

Night Sky Note for July 13, 2014

Sunday, July 13, 2014
Mars is 1.3 degrees to the above of Spica. (closest approach)

Night Sky Note for July 12, 2014

Saturday, July 12, 2014
Mars is 1.4 degrees to the upper right of Spica.

Night Sky Note for July 11, 2014

Friday, July 11, 2014
Mars is 1.6 degrees to the upper right of Spica.

Night Sky Note for July 10, 2014

Thursday, July 10, 2014
Mercury is 8 degrees to the lower left of Venus. Look ENE 45 minutes before sunrise.

Abrams Planetarium Night Sky Notes