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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


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

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