Jupiter remains the dominant planet in the night sky high up in Gemini. It is actually best placed to observe for quite a few years – well clear of more turbulent air found lower down.
Through a telescope Jupiter is a rewarding object to view, especially the first week of March when there are several transits of Galilean moons across the disk so that the shadow of the moon will be visible.
The great red spot is also turned towards us during the mid evening period. Not surprising then that National Astronomy Week runs from March 1–8 with Jupiter as the focal point.
Our moon lies nearby Jupiter on the 6th. Mars is now visible by late evening low in the southeast, though is still best observed in the dawn sky. The red planet resides in Virgo – to the left of its chief star Spica, which it is in conjunction with on the 31st.
Telescopically Mars exhibits a very small orange disk which will not improve until Mars reaches opposition next month. The moon lies nearby Mars and Spica on the 18th. Saturn and Venus both lie in the dawn sky.
Saturn rises in the early morning hours over in the southeast, whilst Venus is seen as a brilliant object low down in the same direction an hour before sunrise. The moon lies near Saturn on the 21st and Venus on the 27th.
The Spring Equinox
The date of the Vernal Equinox and officially the start spring in the northern hemisphere falls on March 20 this year. This is when the Sun’s path - the ecliptic, first crosses the celestial equator on its apparent journey northwards into the sky. The position of Earth in its orbit around the sun at equinox means that neither of the poles are inclined towards the Sun and so all locations experience equal hours of daylight and darkness - hence the term equinox.
The Vernal Equinox is also known as the ‘First point of Aries’, as the Sun used to stand before the constellation of the Ram when it first crossed the celestial equator. Although still called the ‘first point of Aries’, today its location now resides in Pisces, a consequence of the effect known as precession - the Earth’s slow wobble.
The Dog Star
View to the south at this time of year and your eyes will be drawn to the brilliant sparkling diamond of Sirius, the brightest star in the night sky.
Residing in the constellation of Canis Major- the Greater Dog, located to the lower left of Orion, ‘the dog star’, as it is also known, always appears to twinkle vigorously from the UK. This is not of course due to the star itself, but is caused by our turbulent atmosphere.
Not surprisingly it is not uncommon for Sirius to be the source of mistaken UFO sightings by the ‘night sky unwary’. View Sirius through any optical instrument and it appears a maelstrom of ever changing hues.
Throughout human history Sirius has been the most brilliant of stars, an object of wonder and veneration.
To the ancient Egyptians Sirius was revered as the Nile Star, the star of Isis, who’s annual appearance just before dawn at the Summer Solstice heralded the coming rise of the Nile into flood, an event upon which Egyptian agriculture and hence, society depended.
In the ancient Greek and Roman world, the rising of Sirius was regarded as unfortunate, its searing light thought to add to the scorching heat of July and August and attributed in bringing forth ‘fever and madness’ during the so called “dog days of summer”. Sounds familiar? The name Sirius is actually derived from a Greek word meaning “sparkling or scorching one”
As for the Sirius itself, compared to our Sun it is roughly double in size and approximately 20 times more luminous, however, the chief reason for Sirius’s prominence in our skies is due to its proximity, a mere 8.5 light years away. Overall, Sirius is the 5th nearest star to us, and of these only it and Alpha Centauri (which is not visible from Britain) are readily visible to the naked eye.
Sirius is actually a binary star, travelling through space with a companion dubbed the ‘Pup’. This is the degenerate core of a star that once might have resembled our Sun.
Such stars are called White Dwarfs and are extremely small, but have incredibly high densities; the Pup for instance is estimated to be just 20,000 miles across, but a thimble full would weigh several hundred tons.
Although technically visible in a modest scope, the overwhelming glare of Sirius itself renders the pup undetectable. Still, it remains the most famous member of this strange class of stars. Do check out the dazzling Dog Star – but don’t go barking mad!
The Late Winter Sky; A Celestial Ramble
The late winter sky offers up a feast of celestial delights for even the most casual of observers. Our celestial ramble begins in the west, where during the early part of the evening you will find the autumnal groups of Andromeda and Pegasus stretching down towards the horizon.
Higher up, either side of Andromeda lie Perseus; a group of stars that resemble a distorted figure Pi symbol, and the distinctive ‘W’ pattern of Cassiopeia. Overhead, close by the zenith throughout early evening sits brilliant Capella, leading star in Auriga the charioteer.
Low to the north, two stars attract the eye. Normally associated with balmy summer nights, the circumpolar stars of Vega (N) and Deneb (NNW) are members of the ‘summer triangle’, but are visible all year round from our latitude.
Unwary sky watchers may assume brilliant Vega to be the North Star, a case of mistaken identity also shared by Capella during the summer months. The proper north or pole star is located some 3 hand spans above, in Ursa Minor, the little bear. If you are unsure, use the ‘pointer’ stars in the bowl of the Plough; the familiar 7 star ‘saucepan’ shape presently located high in the NE during the evening, to identify Polaris.
Ranged across the southern aspect, a glittering array of wonderful constellations are now at their best. Taurus leads the charge into the western half of the sky.
The Bull is located high in the SW and identified by the “V” outline of the Hyades star cluster complete with fiery Aldeberan. Just ahead of Taurus, the exquisite star cluster of the Seven Sisters or the Pleiades is well worth viewing in binoculars.
Below left of Taurus sits majestic Orion, highlighted by brilliant Rigel and ruddy hued Betelgeuse, together with the 3 belt stars, As the hunter marches into the SSW, following behind, low in the South, the most prominent of all night stars, sparkling Sirius, the “dog star” commands attention.
Some distance above, solitary Procyon, in the lesser dog, is also conspicuous. A little higher still and due south, Gemini, marked by Castor and Pollux; the twins, occupy centre stage. The brilliant ‘guest star’ within Gemini is the planet Jupiter.
To the east the first celestial shoots of spring are already present, led by the zodiacal constellation, Cancer - the crab, which scuttles after Gemini. Light polluted skies or strong moonlight will drown out this crustaceans dim stars. Check out the lovely star cluster known as the ‘Beehive’, seen as a misty spot with the eye.
“And next the crab, the Lion shines” just part of a rhyme for remembering the order of the Zodiacal groups, and it is Leo the Lion that stands guard of his territory east of Cancer.
Leo is easily identified by bright Regulus situated at the base of a “Sickle” pattern, one of the heavens more obvious asterisms. A hands span to the right of Regulus, look for a distinctive knot of fainter stars that mark the head of Hydra, the largest constellation in the sky, whose tail will not rise until well after midnight. The Water Snakes chief star, Alphard is located a hand span below the head and is reasonably conspicuous.
Finally, later in the evening look in the east for the second brightest star visible from our shores, Arcturus, after its short winter break below the N horizon, this lovely orange star in Bootes is actually considered a summer visitor, and an early sign for watchers of the night sky that warmer and drier days are just around the corner, we hope.
The next meeting of Whitby and District Astronomical Society will be on March 4 (Tuesday) at Whitby Community College, main block, room H1 from 7.30pm.
Open nights at the Bruce Observatory are on Sunday 2 and Mar 7 and 9th from 7pm – weather permitting.
Anyone interested in observing the winter night sky are most welcome to come along.