Interesting object in the southern sky Chart for the southern sky in June
Interesting objects in the Eastern Sky Chart for the East sky in June
Jupiter appears in the eastern sky in early twilight shining with a steady golden light. On the opposite side of sky is Sirius, twinkling like a diamond; setting early. Canopus is in the southwest sky. Crux, the Southern Cross, and the Pointers, Beta and Alpha Centauri are south of overhead. Scorpius, upside down, is midway up the eastern sky. Below it is Sagittarius, its brighter stars making 'the teapot'. Low in the northwest Saturn makes an eye-catching pair with Regulus, the head star of Leo the lion. Mars is similar in brightness to Regulus but orange-coloured. Mars is moving rightward (eastward) against the background stars. By the end of June it will be just below Regulus. Orange Arcturus in the northeast often twinkles red and green.
Jupiter is the brightest star-like object in the night sky. It appears low in the east at early dusk and is north of overhead by the morning hours. Binoculars show the disk of Jupiter and one or two of its large moons like faint stars very close to the planet, above left and below right. A small telescope easily shows all four moons but often not all at once. Jupiter is 12 times wider than the earth and 320 times heavier. Just now it is 640 million kilometres away, nearly as close as it gets.
Sirius appears midway down the western sky at dusk, often twinkling like a diamond as the air breaks up its white light. Sirius is the brightest star in the sky both because it is relatively close, nine light years away, and 23 times brighter than the sun.
Crux, the Southern Cross, is south of the zenith. Beside it, and brighter, are Beta and Alpha Centauri, often called 'The Pointers' because they point at Crux. Alpha Centauri is the closest naked-eye star, 4.3 light years away. A telescope shows it is a binary star: two suns orbiting each other in 80 years. Beta Centauri and many of the stars in Crux are hot, extremely bright blue-giant stars hundreds of light years away.
Canopus , above and left of Sirius, is the second brightest star. It is a truly bright star: 13 000 times the sun's brightness and 300 light years away. Canopus is a 'circumpolar star' from New Zealand: it never sets. During the night it swings down toward the southern skyline then moves up into the eastern sky.
Scorpius is midway up the eastern sky, lying on its back. Its brightest star is orange Antares, marking the scorpion's heart. Antares is a red giant star: 600 light years away and 19 000 times brighter than the sun. Red giants are much bigger than the sun but much cooler, hence the red colour. They are dying stars; wringing the last of the thermo-nuclear energy from their cores. Antares will end in spectacular supernova explosions in a few million years.
The Milky Way is brightest and broadest in the southeast toward Scorpius and 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 shows many clusters of stars and some glowing gas clouds, particularly in the Carina region, to the right of Crux, and in Scorpius. Relatively nearby dark clouds of dust and gas make holes and slots in the Milky Way.
The Large and Small Clouds of Magellan, LMC and SMC,are midway down the southern sky, easily seen by eye on a dark moonless night. They are two small galaxies about 160 000 and 200 000 light years away. Both are satellite galaxies of the Milky Way, orbiting in about two billion years. They are only a fraction the mass of our galaxy but still contain billions of stars.
Arcturus, toward the north, often twinkles red and green as the air disperses its orange light. It is 120 light years away and 37 times brighter than the sun.
Arcturus , in the northeast, is the fourth brightest star in the sky, and the brightest seen in the northern hemisphere. It is 120 times the sun's brightness and 37 light years away. When low in the sky it often twinkles red and green as the air disperses its orange light. Arcturus is cutting across the general stream of stars that orbit in the plane of the Milky Way. It probably belonged to a small galaxy that was absorbed by our galaxy.
Jupiter, shining with a steady golden light, is low in the east at dusk. On the opposite side of the sky Sirius twinkles colourfully before it sets mid evening. Canopus is in the southwest, swinging down under the pole during the night. Orange Arcturus in the north often twinkles red and green. Saturn makes an eye-catching pair with Regulus in the northwest with Mars closing on them through the month. South of overhead, are the Southern Cross (Crux) and the pointers Alpha and Beta Centauri. The Scorpion is on its back midway up the eastern sky with Sagittarius below it. The Milky Way is broad and bright in the east and can be followed up through Crux and Carina and on into the west.
Centaurus, with the bright 'Pointers', and Crux, the Southern Cross are south-east of overhead, the tightest grouping of bright stars in the sky. Originally Crux was the hind legs of the Centaur, the horse-man of Greek mythology. The complete Centaur, with bow, is outlined at left. It was only in the 17th Century that Crux was split off as a separate constellation. The slow wobble of Earth's axis allowed this part of the sky to be seen from more northerly places in ancient times. The fainter Pointer and the three bluish-white stars of the Crux are all super-bright stars hundreds of light years away. Alpha Centauri is just 4.3 light years away and the reddish top star of Crux is 90 light years from us.
Omega Centauri, also southeast of the zenith, is a globular cluster, a ball-shaped cluster of millions of stars. Its total mass is six million times the sun's. It is 17 000 light years away and 200 light years across. Globular clusters are very ancient, around 10 billion years old, twice the age of the sun. Omega Centauri is the biggest of the hundred-odd globulars randomly orbiting our galaxy. It may originally have been the core of a small galaxy that collided with the Milky Way and was stripped of its outer stars.
47 Tucanae, by the SMC, is a similar sort of cluster 16 000 light years. Though it appears near the SMC it has no connection, being 15 000 light years away.
The Coalsack nebula, left of Crux, looks like a hole in the Milky Way. It is a cloud of dust and gas 300 light years away, dimming the distant stars in the Milky Way. Many "dark nebulae" can be seen along the Milky Way, appearing as slots and holes. These clouds eventually form new stars.
The Jewel Box is a compact cluster of young bright stars about 7000 light years away. The cluster formed less than 10 million years 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, a luminous spot in the Milky Way to the right of Crux, is a glowing gas cloud about 8000 light years from us. The thin gas glows in the ultra-violet light of nearby hot young stars.
The golden star in the cloud, visible in binoculars, is η [Greek 'e'] Carinae. It is estimated to be to be 60 times heavier than the sun. It is a million times brighter than the sun but is dimmed by dust clouds around it. It is expected to explode as a supernova in the next few thousand years. Many star clusters are found in this part of the sky.
The Large & Small Clouds of Magellan (LMC and SMC) appear as two luminous patches, easily seen by eye in a dark sky. They are two galaxies like the Milky Way but much smaller. Each is made of billions of stars. The Large Cloud contains many clusters of young luminous bright stars seen as patches of light in binoculars and telescopes. Both clouds are about 160 000 light years away, very close by for galaxies.
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 in the sky. It is 13 000 times brighter than the sun and 300 light years away. Sirius, low in the east on spring evenings, is the brightest star in the sky.
A telescope also shows stripes across the oval disk of Jupiter. They are light and dark zones in Jupiter's clouds. The clouds are dark where they are warmed (to -140 C) by gas rising from Jupiter's interior and white where the gas is cold and sinking. The planet's fast spin forces these convection zones into narrow strips. Jupiter spins quickly, once in 10 hours, so it is slightly stretched out at the equator. Just now Jupiter is 650 million km from us. It is five times our distance from the sun.
Jupiter is by far the biggest of the planets. It has a mass or weight 320 times that of Earth: twice the mass of all the other planets put together. It is 11 times wider than Earth. If Jupiter was hollow then 1300 Earths could be squashed inside it. It is made mostly of hydrogen. In the outer parts of the planet the hydrogen is a gas and makes the clear 'air' that the clouds float in. Deeper down the hydrogen is squeezed into a solid. It has the properties of a metal and conducts electricity. This gives Jupiter an extremely strong magnetic field. The magnetism traps particle radiation like the Van Allen belts around the Earth but much more energetic. Spacecraft passing or orbiting Jupiter must have their sensitive electronics specially shielded.
Much higher than Jupiter and to its left is Antares, an orange-red star. Antares means 'rival to Mars' in Greek. Much of the time Mars looks about the same brightness and colour. (Mars is low in the evening sky to the northwest setting mid evening.) Antares is a red-giant star: 600 light years away, 19 000 times brighter than the sun, and big enough to fill Earth's orbit.
This part of the Milky Way is broad and bright as we are looking to the centre of the galaxy. The actual centre, 30 000 light years away, is hidden from our view by intervening dust clouds. The nearer clouds make gaps and slots along the Milky Way. Some of the central bulge of the galaxy is glimpsed in gaps between the clouds. At the very centre lies a black hole three million times the sun's mass but only the size of our solar system. Infra-red telescopes, peering through the dust, show stars orbiting the invisible black hole at high speed.
Antares marks the heart of the Scorpion. Its tail, upside down, stretches out to the right: the 'fish hook of Maui' in Maori star lore. At the highest point of the tail is a large and bright cluster of stars (NGC 6231) looking like a small comet. It is around 6000 l.y. away. Its brightest stars are 60 000 times brighter than the sun. Below the Scorpion's sting is M7 a cluster obvious to the eye and nicely seen in binoculars. M7 is about 800 l.y. away and around 260 million years old. Left of M7 and fainter is M6, the 'butterfly cluster', around 1300 l.y. away. Other clusters worth a look in binoculars are M21, M23, NGC 6167, and NGC 6193. The 'M' objects were listed by the 18th Century French astronomer Messier.
Further down the Milky Way is the glowing gas cloud M8, left of Sagittarius's "Teapot' lid. Nearby is M20, the Trifid Nebula, a small glowing patch in binoculars. Other nearby nebulae are M16 and M17.
Globular clusters, spherical clouds of ancient stars, are found throughout the region. One of the brightest is M4 by Antares. At 10 000 l.y. away it is one of the closest globulars, though NGC 6397 is probably closer. In binoculars and small telescopes they appear as round fuzzy spots. Other globulars marked on the chart are M10, M12, M19, M22, M55, M62, M80 and NGC 6541. The concentration of globular clusters here was an early clue that the centre of the galaxy lay in this direction.
