Sky Notes for June 2014 with James Abbott
The Summer Solstice takes place on June 21st just before local noon. The Sun will beam down from an altitude of nearly 62 degrees, its highest point in the sky for the whole year. The North Pole of the Earth’s axis faces towards the Sun and everywhere within the Arctic Circle has 24 hours of daylight.
The changing seasons that follow the annual cycle of the Sun’s height in the sky are pronounced at our latitude and are of course due to the fact that the Earth’s axis is tilted by 23 degrees. A smaller tilt would mean less seasonal variation and a larger tilt more extreme variations. Fortunately the Earth’s tilt is fairly stable, but our near neighbour Mars is less fortunate. Its tilt is currently similar to Earths at 25 degrees, but it can swing wildly away from this over periods of millions of years. The difference is that we have a large Moon which helps stabilise our tilt whereas Mars only has 2 tiny satellites which do not.
Jupiter finally departs the evening skies in early June and might be seen early in the month very low down in the North Western twilight.
Mars remains in Virgo and continues to fade throughout the month as its distance from Earth increases, though it remains a fairly bright object visible all evening and will be edging towards the bright star Spica as the month progresses. By the end of June the disc diameter of Mars drops below 10 arc seconds.
Also in Virgo are Ceres and Vesta, about 2.5 degrees apart at the start of the month but less than 0.5 degrees apart by months end and on their way to a close approach of just 10 arc minutes on July 5th. Having mapped Vesta, the NASA DAWN mission will arrive at Ceres in 2015. It will be a bonanza year for fans of small icy worlds as the NASA New Horizons mission will be at Pluto in July 2015.
In mid-month Saturn is in the South during the late evenings and rather low down. This is a good time to have a look for Antares which is in the same area of the sky. Antares is the brightest star in the Southern constellation of Scorpius and is a red supergiant that will one day explode as a supernova. It is an enormous star, even larger than Betelguese and with a total radiation output over the electromagnetic spectrum around 60,000 times greater than the Sun. At 11.30 pm mid-month Antares is due South, just over 20 degrees to the left of, and below, Saturn. Scorpius is one of the finest constellations in the entire sky and can be fully seen from countries further South such as France, but from Essex is truncated by the horizon and it needs a clear transparent night to see some of the stars in the constellation. To the left (East) of Scorpius is Sagittarius, where we are looking towards the centre of our Milky Way galaxy.
The Moon makes close passes in the sky of several of the planets this month – just a few degrees from Mars on the evening of the 7th and again a few degrees from Saturn on the evening of the 10th. Full Moon is on the night of the 12th/13th. During this short summer night the Moon will only reach 18 degrees above the horizon.
Late June brings both the longest evenings of the year and often the best chances of observing noctilucent clouds. The first NLC were seen this year on May 24th by the NASA AIM satellite. One of the best times to try to see them is between 10.30 pm and 11 pm, looking towards the North West and low down – so a clear horizon is required. The clouds vary between looking like cirrus clouds faintly lit, to bright bluish complexes of streaks and swirls. At the extreme height these clouds form, the atmosphere is very thin and well below minus 100 C, something to consider when viewing them on a warm summer evening !
Posted on 2 June, 2014, in Astronomy News, astrophotography, Observing News, Popular Science, Society News, Stargazing. Bookmark the permalink. Comments Off on Sky Notes for June 2014 with James Abbott.