Eye on the Night Sky over Whitby

The night sky chart of skies as seen above Whitby
The night sky chart of skies as seen above Whitby

Jupiter finally succumbs to bright evening twilight and is lost to view towards the end of the month.

Jupiter will return to the morning sky later next month.

On the 12th/13th Mars is in conjunction with Spica for the final time this year, after which it races away from the chief star in Virgo, continuing in prograde motion and heading in the direction of Saturn.

Telescopically Mars appears rather small with just a hint of surface detail visible.

Saturn is well placed in the evening sky, visible across in the SSW midway between Mars and the conspicuous orange star Antares in Scorpius.

Through a scope the stunning rings should be quite apparent - one of nature’s finest sights. Look for Titan, Saturn’s largest moon as a speck of light nearby, it circles round Saturn twice a month in an anti clockwise direction. Saturn lies near our moon on July 7.

Let us stay in the evening sky, and in the vicinity of Mars, where the two large asteroids Ceres and Vesta lie very close to one another. That evening they will easily be seen in the same x7 or x10 binocular field, but you will need to observe around 11pm when skies are sufficiently dark to pick them out. Use the charts to help track them down.

The pair cross paths later in the month, but Vesta will have pulled away from Ceres by then.

Mercury makes an appearance in the dawn sky after July 20. Look for it low down in the NE just a few degrees above the horizon and lower left of much brighter Venus, which may serve as a guide. A slim crescent moon lies off to the right of Venus on July 24. You will need to be up around 50 minutes before sunrise to spot them.

Next Moon Phases - Full 12th, Last Qtr 19th, New 26th

Stellar Incognito

The shorter summer nights allow little opportunity for the casual observer to readily identify many of the constellations on show; indeed only a handful or so of stars are visible before most people have gone to bed! Just identifying these few stellar jewels scattered across the heavens can be tricky.

Yet, not all are new, unfamiliar stars, some are old friends now located in a different aspect of the sky.

Time then to put a name to the new arrivals and unmask our stellar friend’s incognito.

We’ll start high to the NE with the second brightest star currently visible in the night sky, Vega - chief star in Lyra - the Harp. Vega resides 27 light years away and may be considered a young, very hot adolescent star, a fact reflected by its lovely steely blue-white hue.

Back in the 1980s a debris disk was discovered by infra red satellite surrounding Vega, which astronomers believe to be left over material after the formation of Vega itself. This may eventually coalesce into a planetary system. Our next star, Altair, is located across in the ESE in the constellation of Aquila the Eagle.

Also considered a young star, Altair is a star in a spin, an unusually rapid one, rotating in less than six hours. As a result Altair is decidedly oblate - rugby ball shaped.

Altair also has the distinction of being the nearest first magnitude star visible from Britain during the summer, a mere 16 light years away.

Both Altair and Vega play a prominent role in one of the few star legends to have come down to us from ancient China, the appealing story of the Weaving girl and the Herd–boy.

According to this tale Vega, the weaving-girl and Altair the herd-boy, were deeply in love and lost in amorous dalliance neglected their duties. The two were suitably punished, eternally separated by the celestial river, the impassable Milky Way.

Only once a year, on the seventh night of the seventh moon were the lovers allowed to meet when a bridge of doves temporarily spanned the river of stars.

Close by ruddy Mars, the bright spring star Spica, or alpha Virginis is inexorably heading toward the western horizon. Spica is a close spectroscopic binary star (you won’t split them using a telescope) over 260 light years distant. Both components are larger and much hotter than our sun.

Capella, our next port of call, lies in the constellation of Auriga – the charioteer and is actually visible all year round from our latitude (circumpolar).

During the summer months Capella is located low above the N horizon, hence it is often mistaken for the North Star. Like Spica, Capella is an extremely close binary system, the two components separated by just 7 million miles. Both stars are similar in type, temperature and age to our own Sun; ie middle aged, but considerably larger. They are situated 46 light away.

Next up is the brightest star visible throughout summer and early autumn, Arcturus, presently located high in the SSW. In the distant past solitary Arcturus would have quite resembled our own sun, but has evolved into an orange giant’ star 30 times its original diameter.

At 37 light years Arcturus is the nearest example of this type of star. Arcturus would however be dwarfed by our next luminary, which is only briefly visible from our shores during midsummer. Deep orange Antares - the ‘rival of Mars’ is situated in the constellation of Scorpius, located very low to the south as twilight deepens.

Classed as a red super giant, Antares has a diameter estimated to be around 250-300 million miles, ten times the size of Arcturus and lies over 350 light years away. Unlike Arcturus, Antares will eventually bow out in a blaze of glory, a fate that will definitely befall our final destination

Deneb, in the constellation of Cygnus is currently located mid -way up in the NE. Along with Vega and Altair, it forms the famous ‘summer triangle’ asterism. Of the stars visited, Deneb is the faintest, but appearances can be deceptive. Its immense distance of around 1700 light years hide Deneb’s true nature, a genuine stellar heavy weight amongst our luminaries, 25 times more massive and 140 thousand times more luminous than our Sun.

In terms of true age Deneb is still very young, but is converting energy at such a prodigious rate that in less than 50 million years it will fully evolve into a star possibly twice the size of Antares, ending its days in cataclysmic fashion as a supernova.

Then, for a few weeks Deneb will outshine all but the Sun and Moon and our descendants will marvel at the new light in the night, and day sky.

The next public star parties - weather permitting, take place on the West Cliff – adjacent to Cook’s statue on July 12 and 19 from 9.30pm

For more information contact Mark Dawson on (01947) 605516 or e-mail spanton33@talktalk.net

You can also visit www.whitby-astronomers.com