DCSIMG

Eye on the Night Sky over Whitby

Night Sky for April

Night Sky for April

Mars reaches opposition on April 8 when, for the first time in two years, the red planet will be closest in its orbit to Earth and visible all night.

That said, it is not a particularly close opposition and through a telescope the Martian disk will only appear 15 arc seconds across, less than a third of Jupiter’s.

This means surface features will be quite difficult to make out through modest scopes, although the north polar cap should be readily apparent as well as darker ‘mottling’. Appearing half the brightness of Jupiter, Mars resembles a conspicuous ‘orange star’ over in the South east, upper left of Spica during the evening.

It lies due south by midnight. The Moon lies below Mars on the 14th.

One final cautionary note, should you come across an article on the Internet or via e-mail suggesting that Mars may be the size of the Full Moon, please ignore.

Jupiter remains the brightest planet in the night sky high up in Gemini and although Mars may well be the centre of attention in April, Jupiter is still the most rewarding planetary target to observe through a telescope given the dynamic nature of the Galilean moons, shadow transits, banding features and the great red spot.

The Moon is nearby on the 6th.

Saturn is also rising just before midnight, vying for attention with Jupiter and Mars. Telescopically, it is best observed in the early morning hours when higher in the sky and clear of any turbulent air.

By dawn Saturn lies over in the SW. The moon lies near Saturn on the 17th. Venus is seen as a brilliant object low down in the SE an hour before sunrise. On April 12th it lies just over half a degree above Neptune.

The moon lies nearby on the 25th.

The month’s most prolific shower, the Lyrids, peak on the morning of the 22nd.

Hourly rates are at best around the 15-20 mark, but actual observed rates will be less than this (7-10) View in the early morning hours of the 22nd

The Lion and the Water Snake

If Orion is regarded as the ‘signpost’ group and ‘hub’ of the winter sky, so Leo the Lion is the signature group of the spring sky. The Lion can be located due south by 10pm and is a splendid constellation.

The head and mane are marked by a distinctive stellar asterism known as the ‘sickle’ – the gardening implement, although some people regard it as a backwards question mark.

To the left of the sickle, a ‘triangle’ of stars depict the hindquarters of Leo. Leo’s chief star resides at the base of the sickle and is faintest of the 1st magnitude stars, though still prominent.

Regulus sits almost on the ecliptic and as a consequence can be joined in close proximity by the moon and planets, occasionally being occulted by them. Regulus lies almost 70 light years away.

In mythology Leo was the lion raised by Hera - Queen of the gods. The Lion’s coat was said to be impervious to fire and metal weapons. In the first of his twelve labours, Hercules was given the task of slaying the beast then ravaging the region of Nemea.

After trapping the lion in a cave Hercules clubbed it to death. In honour of Hercules, Zeus placed the lion in the heavens.

Our next destination is associated with the 2nd labour of Hercules, in which he dispatched yet another monster raised by Hera; the Lernaean Hydra, a multi-headed snake empowered with the ability to re-grow two heads.

Hercules used his sword to sever the heads and flaming arrows to cauterise the neck-stumps in an effort to them from regenerating. Hera; who saw that her ‘pet’ was in trouble, sent a giant crab (Cancer) to assist Hydra. In the ensuing battle Hercules not only killed the Hydra, but he also crushed the giant crustacean.

A distraught Hera then placed both monstrous creatures in the heavens. In the sky Hydra’s chief claim to fame is that it is now the largest constellation in the heavens, though not the most conspicuous.

To view it in its entirety you will have wait until after 11.30pm, by which time the head is visible in the SW, while the tail is only just clearing the SE horizon.

The writhing heads are marked by a distinctive, though rather faint loop of stars to the right and slightly below Regulus. Hydra’s brightest star; Alphard- the ‘solitary one’, may be located almost a hands span southeast of this.

Toward the tail of Hydra, two small but original constellations rest on snakes body; Corvus the crow and Crater the cup. The outline of Crater does quite resemble that of a goblet – but the stars are rather faint and therefore difficult to trace in light polluted skies.

Corvus the Crow is more prominent; a quadrilateral grouping of stars that, mariners and astronomers alike refer to as ‘Spica’s spanker’ - a spanker being a type of sail and Spica being the nearby chief star in Virgo.

Both small constellations are linked by one legend in which Apollo sent his pet white crow to fetch a cup of water. The bird flew off with the cup in his talons, but tarried, waiting for the fruit of a fig tree to ripen.

On his return Corvus tried to convince Apollo that Hydra the water snake had delayed him. Apollo did not believe the bird and in a rage turned the crow black, dispatching him to the sky to be near Hydra and Crater, which is just out of the thirsty bird’s reach.

The Stellar Dozen

The lighter evenings of April offer up an interesting observing stellar challenge for all levels of experience, one that involves spotting first magnitude stars; those ranked brightest in the sky. Piercing the spring evening twilight, no less than a dozen are currently visible, more than at any other time of year.

However the window of opportunity in which to identify these stellar jewels is limited and rapidly diminishes as we head deeper into April, from little over an hour at the start, to just fifteen minutes by mid month.

You will require a clear horizon all round and complicating matters further are a number of bright planets.

At the start of April evening twilight deepens around 9pm. To accomplish the challenge two stars are key, Rigel and Spica. As Rigel is setting in the west, so Spica is rising in the Southeast, therefore timing is critical, i.e. spotting both above the horizon before picking off the other stars. First, look across to the west where the mighty hunter Orion is about to lose his right toe;- marked by bright white Rigel, (1) below the horizon.

Then turn to the SE where hopefully you should spot two bright stars. The upper orange hued one is actually Mars, below which lies white Spica (2) chief star in Virgo. So you will need to be quite sharp in spotting these. Now press on! Above Rigel, Orion’s three belt stars are aligned parallel to the west horizon, but the next star on our list, the conspicuous orange hue of Betelgeuse (3), is located above them.

A hand span to the right of Betelgeuse and slightly closer to the horizon another orange star, Aldebaran (4) chief star in Taurus is visible. The brightest star in the night sky, sparkling Sirius (5) is quite unmistakable low in the WSW.

Having picked out this first clutch of stars, there is no time to waste, so raise your gaze somewhat higher, to pick out the next wave of luminaries.

Starting in the SW again seek out the bright solitary white hue of Procyon (6) in Canis Minor located above Sirius and to the left of Orion. Due west and higher still, Castor (7) and Pollux denote the twins of Gemini, which is descending feet first down toward the horizon.

The conspicuous ‘star’ within Gemini is of course Jupiter. At a similar altitude to Gemini further across in the WNW shines brilliant Capella (8) in Auriga, the only first magnitude winter star to remain visible all year round, being circumpolar from our latitude. Capella will spend the summer months arcing low above the north horizon.

Due south, midway up, you will encounter bright Regulus (9) in the ‘sickle’ or ‘backwards question mark’ asterism of Leo, whilst due east brilliant Arcturus (10) in the constellation of Bootes is very noticeable, its soft orange hue contrasting markedly with Sirius, the only star of the baker’s dozen brighter than it. Now for a test within a challenge, see how far into April you can spot both Sirius and Arcturus above the horizon at the same time.

Our final two stars are located low in the north. The bright steely blue hue of Vega (11) resides in the constellation of Lyra and is located in the NE. Vega almost rivals Arcturus in apparent magnitude, but unlike the ‘guardian of the bear” it is circumpolar from Whitby’s latitude. Our final star, Deneb (12) is located just above the NNE horizon and appears much less brilliant than Vega but is by far the most distant and massive of the stars visited. It too is circumpolar and along with Vega constitutes two of the three stars forming the ‘summer triangle’. In less than three months, only Arcturus, Capella, Deneb and Vega will remain of our original stellar baker’s dozen, the rest having set. So pick a clear night within the next two weeks and spend 5 minutes in the company of stellar greatness

The Bruce Observatory at Whitby College is open on April 6, 13 and 20 from 8pm, 8.30pm and 9pm respectively.

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

Visit www.whitby-astronomers.com

 

Comments

 
 

Back to the top of the page