The Evening Sky in June 2017

Download a PDF containing this chart, additional charts for specific areas of the sky and descriptions of interesting objects visible at this time of year.

The Evening Sky in June 2017

Jupiter appears in the northeast sky soon after sunset, the brightest 'star' in the sky. It shines with a steady golden light. Sirius, the brightest true star, appears soon after, low in the west. It sets around 9 pm, mid-month, twinkling like a diamond. Canopus, the second brightest star, is in the southwest. As the sky darkens cream-coloured Saturn appears due east with orange Antares above it. Arcturus, another orange star, appears in the lower north sky, often twinkling red and green when it is low in the sky.

Sirius appears bright both because it is 20 times brighter than the sun, and because it is relatively close at nine light years*. Canopus is a truly bright star, 310 light years away and 13,000 times brighter than the sun. Canopus is a 'circumpolar' star: it circles the South Celestial Pole (SCP on the chart) but never sets.

Jupiter's disk and four 'Galilean' moons can be seen any telescope. We are seeing the moons' orbits nearly edge-on so they appear to move back and forth like beads on a string, swapping places night to night. Io, the closest to Jupiter, orbits in 1¾ days. Callisto, the farthest of the four, takes nearly 17 days to complete an orbit. Jupiter is 750 million km away. Saturn is the brightest 'star' in the eastern sky. A small telescope shows its rings and its biggest moon, Titan, orbiting about four ring-diameters from the planet. Saturn is 1,350 million km away.

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. Beta Centauri and many of the stars in Crux are hot, extremely bright blue-giant stars hundreds of light years away. They are members of a group of stars that formed together then scattered. The group is called the Scorpio-Centaurus Association.

Antares, the orange star above Saturn, marks the scorpion's body. It 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 orange- red colour. Though hundreds of times bigger than the Sun, Antares is only about 20 times the Sun's mass or weight. Most of the star's mass is in its hot dense core. The rest of the star is thin gas. Red giants are dying stars, wringing the last of the thermo-nuclear energy from their cores. Below Scorpius is Sagittarius, its brighter stars making 'the teapot'.

The Milky Way is brightest and broadest in the southeast toward Scorpius and Sagittarius. It remains bright but narrower through Crux and Carina then fades in the western sky. 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 find many clusters of stars and some glowing gas clouds. Relatively nearby dark clouds of dust and gas look like holes and slots in the Milky Way. There is a well-known dark cloud called The Coalsack by the Southern Cross. It is around 600 light years away. The dust, more like smoke, comes off old red stars. These clouds eventually coalesce into new stars.

The Clouds of Magellan, LMC and SMC, in the lower southern sky, are luminous patches easily seen by eye in a dark sky. They are two small galaxies about 160 000 and 200 000 light years away. The Large Cloud is about 5% the mass of the Milky Way; the Small Cloud is about 3%.

Brilliant Venus (not shown on the chart) rises in the eastern sky before 4 a.m. at the beginning of the month, later at the end. At the end of June Venus will be directly above the Matariki/Pleiades star cluster. The Moon will be near Venus on the 21st, enabling the planet to be found in the daylight sky by naked eye. At 11 a.m. that morning the Moon and Venus will be 45 degrees left of the sun and level with it. (45 degrees is roughly two hand-spans at arm's length.) Mercury appears below and right of Venus, the brightest 'star' in the region, at the start of the month. It sinks lower in the dawn twilight, disappearing around the 10th.

*A light year (l.y.)is the distance that light travels in one year: nearly 10 million million km or 1013 km. Sunlight takes eight minutes to get here; moonlight about one second. Sunlight reaches Neptune, the outermost major planet, in four hours. It takes sunlight four years to reach the nearest star, Alpha Centauri.

Newsletter editor:

Alan Gilmore Phone: 03 680 6817
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Lake Tekapo 7945
New Zealand