The Evening Sky in November 2009

Jupiter is the first 'star' to appear, visible northwest of overhead soon after sunset. Binoculars and small telescopes will show Jupiter's brightest moons above-right and below-left of the planet. Jupiter is around 750 million km away from us now. In late November and into December Mercury is near the southwest horizon at twilight. Around the 21st Mercury, white and much brighter, will pass to the right of Antares.

Canopus, in the southeast, is the second brightest star in the sky. It moves eastward and upward during the night as the stars appear to circle clockwise around the south celestial pole, SCP. Canopus is 300 light years away. Seen up close it would be 13 000 times brighter than the sun.

Sirius rises in the east around dusk. When low in the sky it is shining through a lot of air. Warm and cool cells in the air break its white light into colours, so Sirius twinkles like a diamond. It is the brightest star both because it is relatively close, nine light years away, and 23 times brighter than the sun.

Left of Sirius in the late evening is the constellation of Orion, with 'The Pot' at its centre. Rigel, a bluish supergiant star, is directly above the line of three stars; Betelgeuse a red-giant star is straight below. Left again is a triangular group around Aldebaran making the upside down face of Taurus the bull. Still further left is the Pleiades or Matariki cluster, also called the Seven Sisters, Subaru and many other names. Six or seven stars are visible to the eye; dozens are seen in binoculars. The Pleiades cluster is 400 light years away and around 70 million years old.

Scorpius is low in the southwest with its tail pointed up toward the zenith. The tail is 'the fish-hook of Maui' in Maori star lore. Antares, the heart of the Scorpion, is a 'red giant' star cooler than the sun. Antares is bigger than Earth's orbit but it is mostly very thin gas around a hot dense core.

The Milky Way is low in the sky, visible around the horizon from the northwest, through south into the eastern sky. The broadest, brightest part is in Sagittarius. The Milky Way is our edgewise view of the galaxy, the pancake of billions of stars of which the sun is just one. The thick hub of the galaxy, 30 000 light years away, is in Sagittarius. A scan along the Milky Way with binoculars will show many clusters of stars and a few glowing gas clouds.

Low in the south, Beta and Alpha Centauri, and Crux the Southern Cross. In some Maori star lore the bright southern Milky Way makes the canoe of Maui with Crux being the canoe's anchor hanging off the side. In this picture the Scorpion's tail can be the canoe's prow and the Clouds of Magellan are the sails.

The Clouds of Magellan, (LMC and SMC), high in the in the southern sky, are two small galaxies about 160 000 and 200 000 light years away, respectively. They are easily seen by eye on a dark moonless night. The larger cloud is about 1/20th the mass of the Milky Way galaxy, the smaller cloud 1/30th. That's still many billions of stars in each. The globular star cluster 47 Tucanae appears near the SMC but is 'only' 16 000 light years away. Globular clusters are spherical clouds of stars many billions of years old.

Very low in the north is the Andromeda Galaxy, easily seen in binoculars on a dark night and faintly visible to the eye. It appears as a spindle of light. It is similar in shape to our galaxy but a little bigger and nearly three million light years away.

Mars (not shown) is a bright orange star in the morning sky. It rises in the northeast about 2 a.m. at the beginning of the month; around 1 a.m. by the end. It is small in a telescope.

Interesting Objects in the Southern Sky

Large and Small Clouds of Magellan (LMC and SMC) appear as two luminous clouds, easily seen by eye in a dark sky. They are galaxies like the Milky Way but much smaller. Each is made of billions of stars. The Large Cloud contains many clusters of young bright stars seen as patches of light in binoculars. Both clouds are about 160 000 light years away, very close by for galaxies.

47 Tucanae, looks like a faint fuzzy star on the edge of the SMC. It is a globular cluster, a ball of millions of stars. A telescope is needed to see a peppering of stars around the edge of the cluster. Though it appears on the edge of the SMC it is one-tenth the distance, 15 000 light years away, and is has no connection to the Small Cloud. Globular clusters are mostly very old 10 billion years or more; at least twice the age of the sun. Omega Centauri, very low in the south, is a similar cluster.

 

 

The Tarantula nebula is a glowing gas cloud in the LMC. The gas glows in the ultra-violet light from a cluster of very hot stars at centre of the nebula. The cloud is about 800 light years across. It is easily seen in binoculars and can be seen by eye on moonless nights.

This nebula is one of the brightest known. If it was as close as the Orion nebula then it would be as bright as the full moon.

Canopus is the second brightest star. It is 14 000 times brighter than the sun and 300 light years away.

Alpha Centauri is the closest naked-eye star, 4.3 light-years away. Alpha Centauri is a binary star: two stars about the same size as the sun orbiting around each other in 80 years. A telescope that magnifies 30x shows the pair. (A very faint star, Proxima Centauri, which is slightly closer to us, probably orbits the Alpha pair.)

Omega Centauri, is a globular cluster like 47 Tucanae but bigger. Its total mass is six million times the sun's. It is 17000 light years away and 200 light years across. Globular cluster stars are very old, around 10 billion years, twice the age of the sun.

Coalsack nebulais a cloud of dust and gas about 300 light years away, dimming the more distant stars in the Milky Way. Many similar 'dark nebulae' can be seen, appearing as slots and holes in the Milky Way. These clouds of dust and gas eventually coalesce into clusters of stars.

The Jewel Box is a compact cluster of young bright stars about 7000 light years away. The cluster formed less than 10 million ago. To the eye it looks like a faint star close by the second-brightest star in Crux. A telescope is needed to see it well.

Eta Carina nebula is a glowing gas cloud about 8000 light years away. The golden star in the cloud, visible in binoculars, is Eta [Greek η] Carinae. It is estimated to be to be 60 times heavier than the sun and a million times brighter but is dimmed by dust clouds around it. It is expected to explode as a supernova "soon", that is in the next few thousand years. Many star clusters are found in this part of the Milky Way

The Theta Carina cluster or Southern Pleiades, also called the Five of Diamonds cluster, is a bunch of bright stars on the bottom end of the Diamond Cross. The cluster is about 500 light years away and around 10 million years old. It is a nice sight in binoculars and telescopes.

Interesting Objects in Orion and Taurus

Taurus the Bull and Orion the Hunter are constellations recognised by most northern hemisphere cultures. To see the northern hemisphere pictures turn the chart upside down. The face of Taurus is outlined by the V-shaped Hyades cluster. The brightest star in this group is orange Aldebaran, the name meaning 'the eye of the bull' in Arabic. Taurus's long horns extend down our sky. The Pleiades cluster rides on the bull's back

Orion, in the northern hemisphere view, has a shield raised toward Taurus and a club ready for action. The line of three stars makes Orion's Belt. The line of faint stars above and left of the belt form Orion's Sword in the northern view, dangling from his belt. To most southern hemisphere sky watchers the belt and sword form The Pot, The Iron Pot, or The Saucepan.

The Pleiades / Seven Sisters / Matariki / Subaru, and many other names, is a cluster of stars well known in both hemispheres. Though often called the Seven Sisters, most modern eyes see only six stars. Dozens are visible in binoculars. The cluster is about 440 light years away. Its brightest stars are around 200 times brighter than the sun.

The Hyades cluster is 160 light years away. Its brightest stars (not Aldebaran!) are about 70 times brighter than the sun. Aldebaran is not a member of the cluster but simply on the line of sight. It is 65 l.y. away and 150 times brighter than the sun. Aldebaran is a giant star about 25 times bigger than the sun though only five times heavier. Its orange colour is due to its temperature, around 3500°C The sun is 5500°C.

The Orion Nebula is visible in binoculars as a misty glow around the middle stars of Orion's Sword or the handle of The Pot. It is a vast cloud of dust and gas about 1270 l.y. away and nearly 20 l.y. across. Ultra-violet light from a massive, extremely hot star in the cloud causes it to glow. Some stars in this region may be less than a million years old. The sun, by contrast, is 4.6 billion years old. Stars continue to form in a giant cloud behind the glowing nebula. There are many bright and dark nebulae in this region. The Horsehead nebula, a favourite of astronomy books, is beside the right-hand star of Orion's Belt, but too faint to be seen in small telescopes.

Rigel is a blue 'supergiant' star around 40 000 times brighter than the sun and 800 l.y. away. Its surface temperature is around 20 000oC, giving it a bluish colour.

Betelgeuse is a red giant star 250 times bigger than the sun - wider than earth's orbit! - but only around 20 times heavier, so it is mostly very thin gas. It is around 10,000 times brighter than the sun, about 400 light years away, and has a surface temperature around 3000°.

Sirius is the brightest star, though the planets Venus and Jupiter, and sometimes Mars, are brighter. Sirius appears bright because it is both brighter than the sun and relatively a close 8.6 l.y. away. Sirius was often called 'the dog star' being the brightest star in Canis Major, one of the two dogs that follow Orion across the sky.