June 2015

Sun and Moon

FULL MOON occurs on the 2nd at 18:19 PM. LAST QUARTER (half moon in the morning sky) falls on the 9th. NEW MOON is on the 16th at 16:05 PM. FIRST QUARTER (half moon in the evening sky) falls on the 24th.

On the 16th the young lunar crescent will be visible from a small region in the pacific east of the international date line. On the 17th it will be visible from the US, central and south America, as well as central and southern Africa. It may also be visible under perfect conditions from the Middle East, southern Asia, Australia and Indonesia. On the 18th it will be visible over most of the world.

The Moon will be at perigee (closest approach to Earth) at a distance of 369 712 km on the 10th at  06:40 AM.  On the 23rd at 19:02 PM the Moon will be at apogee (furthest from Earth) at a distance of 404 132 km.

Planetary and Other Events – Morning and Evening

Mercury is visible in the morning sky after the first week of the month. Venus shines brilliantly as an evening star all month, setting around 21:00 PM all  month (times relate to Cape Town).

Mars is not visible during June as it passes superior conjunction (behind the Sun) and is lost in the Sun’s glare for several weeks. Jupiter is visible from dusk until around 22:40 PM (21:00 PM) at the beginning (end) of the month. Note that times relate to Cape Town. Jupiter and Venus will appear as a close grouping during the last few days of the month and into the beginning of July. Saturn is visible from dusk until around 07:00 AM at the beginning of the month. By month’s end it will set around 05:00 AM. Uranus is visible in the mornings, rising around 03:40 AM at the beginning of the month and around 01:50 AM by month’s end. Neptune is also visible in the morning, rising at 00:30 AM at the beginning of the month and at 22:30 PM by month’s end.

Two meteor showers are active in June, the theta-Ophiuchids and the June Lyrids. Observing prospects for both these showers are good. The theta-Ophiuchids are active from the 8th June to the 16th June peaking on the 13th June. They are best viewed between 20:00 PM and 05:30 AM looking between the constellations of Sagitttarius, Scorpius and Ophiuchus. The June Lyrids are active from the 11th June to the 21st of June, peaking on the 16th. They are best viewed between 23:30 PM and 02:00 AM looking towards the constellation of Lyra.

The Evening Sky Stars

Leo the Lion’s upside down question mark should be easy to spot in the NW early in the evening, with the right triangle of the Lion’s hindquarters and tail following in the NNW. Bright orange Arcturus guards the Great Bear (invisible from the Cape except for its feet) from the NE, with the dimmer semicircle of the Northern Crown a bit to the right for an observer looking N. Snaking its way across the sky above the constellations of the Lion, the Virgin and the Crow is the great water monster Hydra, with lonely Alphard at its heart fairly high in the NW at evening’s beginning. Alphard is an orange giant star, 175 light years away and 400 times as bright as our Sun. If Alphard were at the center of our solar system, it would extend halfway to the orbit of Mercury, and we would be toast. Arcturus is a similar star, also an orange giant, which appears brighter in our skies because it’s only 37 light years away – but is really only half as bright as Alphard. It’s always a good idea to remember that the universe is NOT two-dimensional, but that stars are at varying distances from us!

By month’s end the Milky Way follows a path from west to ESE across the southern sky, with the bright stars Sirius and Canopus nearby in the W and SW, and the Large Dog, the great ship Argo, the Cross, the Fly, the Centaur, the Wolf, and the Scorpion tangled in the Milky Way itself. By late June the centre of our Milky Way has begun to rise even in early evening, and by late evening the winter the Milky Way is at its most majestic, with the center of the galaxy passing nearly overhead. Notice the way the brighter stars are mostly in a belt almost, but not quite, coinciding with the Milky Way. This is ‘Gould’s Belt’, showing where young stars in our part of the galaxy have been forming in the last few million years. From outside, our Milky Way galaxy would look like a glowing pancake with a lump in the middle, but the pancake would not be perfectly flat – some parts would appear slightly tilted or warped.

Below the Milky Way are the bright stars Canopus in the SW and Achernar (very low in the SSW), the ‘horn’ and ‘little horn’ stars of African legend.

The Morning Sky Stars

By morning, the Milky Way has nearly set, running near the horizon from north around through the west into the south. Deneb shines in the NW predawn skies of early June, marking the top of the Northern Cross, with bright Vega near the northwestern horizon. In the WNW, Altair is the brightest of the stars of Aquila the Eagle, flying southward through the Milky Way. Low in the WSW and SW are the stars of the Archer and the Scorpion, with the stars of the Pointers and the Cross low in the SSW and S as seen from the Cape. From northern South Africa they will typically be invisible.

Almost overhead in the predawn sky at the beginning of the month is the Southern Fish with its brightish star Fomalhaut (‘mouth of the fish’), the 17th brightest star in the sky. It’s only 25 light years away and about 16 times brighter than our sun. Around it is a celestial doughnut, a giant disk of icy dust four times the diameter of our solar system. But the center, aroundthe star itself, is largely free of this material, possibly because planet formation has swept this area clean.

To the south of Fomalhaut are the stars of the Crane, with bright Achernar a bit further southeast. Canopus rises low in the SE before the Sun in early June, and by late June, bright Sirius is visible low in the ESE as well, while Orion can be seen low in the east before sunrise.

High in the northern sky are the stars of the Great Square of Pegasus. The Fishes are above and to the right of the Square (tied together by their tails). Beyond the Fishes, high in the NNE sky, is the Whale. With the Water Bearer and the Sea Goat to the SW of Pegasus, and the Southern Fish nearly overhead, this is a fairly waterlogged part of the sky.

Nicola Loaring

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