Mars and the Pleiades will be in closest rendezvous in 32 years
As an exciting fresh era of Martian exploration begins with the arrival of three new missions, the planet still features in our evening sky.
This month sees it closer to the Pleiades or Seven Sisters star cluster than during any other approach between 2006 and 2038.
The other major planets are poorly placed, with Venus rounding the Sun’s far side on the 26th and Mercury, Jupiter and Saturn hugging our south-eastern horizon at dawn.
Our charts show Mars sinking in the western sky as it tracks east-north-eastwards in Taurus. As darkness falls on the 1st, though, it stands high in the south-west and 3° or six Moon-breadths below the Pleiades.
Shining at magnitude 0.9, it is equal in brightness to the orange giant star Aldebaran which lies 13° to Mars’ left and is seen against the V-formation Hyades cluster of fainter stars. Over the coming days, Mars slips to the lower-left of the Pleiades, being nearest at 2.7° next Thursday and directly between the cluster and Aldebaran on the 8th.
On the evening of the 19th, look for the 33% illuminated crescent Moon 2.3° belowright of Mars and just onethird of the way between Mars and Aldebaran. Mars dims to magnitude 1.3 by the 31st when it sits between the horns of Taurus and above Aldebaran.
As Mars recedes from 219 million to 263 million km during March, it shrinks between 6.4 and 5.3 arcseconds in diameter, making it too small for useful telescopic study.
The Sun climbs another 12° northwards in March to cross the sky’s equator at 09:37 GMT on the 20th, the moment of our spring or vernal equinox when days and nights are almost of equal length around the Earth.
Our days are lengthening at their fastest rate of the year so our view of the stars and constellations at nightfall is also changing quickly.
Take Orion, for example. As nautical twilight ends on the 1st, and the sky becomes
“Our days are lengthening at their fastest rate of the year so our view of the stars and constellations at nightfall is also changing quickly”
effectively dark, Alnilam, the middle star of Orion’s familiar Belt, stands 33° high and due south as seen from Edinburgh.
By the equivalent time on the 31st, though, it has dipped to 22° in the south-west and during April it slides into our western evening twilight.
Edinburgh’s sunrise/sunset times change this month from 07:04/17:47 GMT on the 1st to 06:46/19:49 BST on the 31st, after our clocks jump one hour forwards to British Summer Time on the 28th.
The Moon is at last quarter on the 6th, new on the 13th, at first quarter on the 21st and full on the 28th.
As the twilight fades on the 14th there is a slim chance of spotting the very young Moon when it is only 2% sunlit and a mere 4° high in the west at 18:50, but probably only visible through binoculars and provided the horizon is exceptionally clear.
It should be much easier on the 15th, when it is 5% illuminated and visible for more than two hours after sunset.
On that evening, and for the ones that follow, look for earthshine as the Moon’s darker side is lit by the almost-full Earth in the lunar sky.
Over the succeeding nights the Moon climbs against the star background but never strays far from the ecliptic, the path taken by the Sun during the course of the year.
Since the planets orbit the Sun in a similar plane to that of the Earth, they, too, keep close to the ecliptic and it is no surprise that Mars is hugging the ecliptic as it passes between the Pleiades and Aldebaran.
Although it is not plotted, the ecliptic continues across our southern chart to pass through Gemini, Cancer, Leo and Virgo, a path that takes it close to the Praesepe star cluster in Cancer, and the bright stars Regulus in Leo and Spica in Virgo.
Praesepe (the Latin for manger) appears as a hazy blob to the naked eye and as a swarm of stars through binoculars, leading to its alternative name of the Beehive.
In all, it holds around 1,000 stars at a distance of some 577 light years.
Regulus lies 79 light years away and consists of four stars grouped as two pairs, though only one, a bluewhite subgiant star, is obvious.
Curling above Regulus is the Sickle of Leo, a reversed question-mark of stars that represent the lion’s head and mane.
Here we find Algieba, 130 light years away and one of the finest double stars in the entire sky.
We need a telescope to divide its pair of striking golden-yellow stars which appear only 4.7 arcseconds apart and take 510 years to orbit each other.
Leo’s body stretches to the left (east) of Regulus to Denebola, the lion’s tail, and includes the third magnitude star, Chertan, which is useful as a signpost for locating the brightest of all the asteroids, the 525 km diameter Vesta, as it comes to opposition on the 4th.
Vesta moves from 1.6° (3 Moon-widths) left of Chertan late on the 1st to lie 1.3° due north (above) Chertan one week later.
At magnitude 5.8, it is an easy binocular object as it approaches within 204 million km of the Earth.
Vesta was orbited by NASA’S Dawn spacecraft in 2011 and 2012 and found to be a remarkable, and perhaps unique, asteroid in that (like the Earth) it is a differentiated world with an iron-rich core overlaid by a rocky mantle and volcanic crust.
The early solar system probably had many similar bodies, dubbed protoplanets, that became the building-blocks of the planets, or were smashed to pieces in collisions.
Despite widespread media coverage claiming that the Co-op would refuse to stock foodstuffs made from gene edited crops or animals, the supermarket this week made it plain that this was not the case.
Steve Murrells, chief executive of the Co-operative Group, said that the news release which had resulted in the coverage “did not reflect the supermarket’s views or approach” - and had been issued without its approval, giving the false impression that it had signed up as a supporter of the #Notinmysupermarket campaign, which is lobbying against the Defra consultation on gene editing.
“Here at the Co-op, we have not adopted a new position on gene editing, nor are we seeking to pre-empt the outcome of the ongoing Government consultation on the regulation of genetic technologies,” said Murrells in a letter outlining the Co-op’s stance.
Responding to a request for clarity from the All Party Parliamentary Group on Science and Technology in Agriculture, he said that the supermarket’s current policy prohibited the use of genetically modified (GM) crops, ingredients or additives in Co-op brand products, and had done since 1999 - but added that the Co-op was “absolutely committed” to scientific and evidencebased policy making:
“Given that genetic modification is one of several technologies and innovations that may help to address the challenges facing our global food system, our view is that there is certainly merit in exploring the benefits of gene editing technology, and particularly the role it could play in improving the sustainable production of food.”