This accompanying Sky Chart is taken from Chris Peats’ excellent site, http://www.heavens-above.com and shows a typical April view for Grand Cayman around 9 pm on 15 April. To use the diagram, rotate the picture so that North is aligned with the N in the picture, a small compass will help. The chart will also work for other dates in April, although for the beginning of the month the chart is better timed for 10pm and at the end of month for around 8pm.
Note first the famous pointer stars in the constellation of Ursa Major (The Great Bear) these are known as The Big Dipper, or the Plough and even The Saucepan where the ‘handle’ points to the Pole Star, Polaris in the constellation of Ursa Minor (The Little Bear). Polaris at our tropical latitudes lies close to the horizon only about 20 degrees in elevation.
The easy recognisable pointers can also help us identify other stars. By using them ‘in reverse’ – that is away from the Pole Star we head towards the constellation of Leo the Lion. This month it lies almost directly overhead and it’s Leo I’d like to talk a bit more about in a bit more detail later on in this article.
For the moment let’s just round off the quick tour by mentioning a two bright stars to the east of Leo, one of which is the planet Saturn. The other slightly fainter but still bright star is Arcturus, which is still the fourth-brightest star in the sky By mid-month the moon will also be a useful guide, although its light will drown out many of the visible stars. To the west of Leo is the bright star of Sirius, the Dog Star”in Canis Major (The Great Dog). This star is, in fact, the brightest star in the sky- both Northern and Southern hemispheres. From here we move further west to the famous Orion constellation – with the three stars in his belt, and one bright, very red star in particular, named Betelgeuse
Leo the Lion
Let’s return to Leo, the Lion . As a constellation goes, it does actually look like an animal. The ‘sickle’ or hook-like pattern represents its mane or head, its front feet represented by a bright-ish star called Regulus and a fainter star called Denebola for the rear feet. The constellation has been in the news recently in that it’s being used by teachers and students in a worldwide experiment on the effects of light pollution. Leo is a fairly recognisable constellation and has been known since antiquity. For example, it was well known by the ancient Egyptians. However, with light pollution, the end result these days can be confusing. Throw in a bright moon and you could start to wonder why the ancients made such a fuss of the stars in the first place.
Globe at night
This is exactly what recent campaigns for dark skies are all about. The Globe at Night programme is an international citizen-science campaign to raise public awareness of the impact of light pollution. The programme has encouraged observations of the constellation to create a world map to be made of the effects of light pollution (see www.globeatnight.org). The site explains that with half of the world’s population now living in cities, many urban dwellers have never experienced the wonderment of pristine, dark skies and maybe never will. Light pollution is obscuring people’s long-standing natural heritage to view stars.
More specifically, here in Cayman many people always remark to me when they know of my interest in astronomy on how dark the skies were after Ivan and how wonderful it was- for a short time at least to see the stars in their full glory. Sometimes Cayman astronomers get lucky if there is a power cut!
Secondly, on a recent trip to Miami last month I went to a regular monthly meeting at the local Science Museum and Planetarium. It was a cloudy evening but the event was packed and handouts were distributed on this very same topic. It seems even in Miami there’s growing concern that we are losing an important part of our heritage. The use of street and home lighting at night is an emotive topic these days; it’s now a complex mixture of security and economic and environmental issues, and more time needs to be made to discuss this. Unfortunately, the relationship isn’t that, shall we say, black and white any more.
Learn your way around
The best way to find your way around the sky is by getting someone to show you. The Cayman Islands Astronomy Society meets at Pedro Castle most months, and we are always happy to see visitors both old and new . We do not charge for the viewings and there’s no catch except that you might get interested in star gazing!
If you do get the bug, you can join the Society to benefit from its additional meetings and resources. Visit our web site http://caymanastronews.blogspot.com Alternatively, contact Nick Kelly on 947-3065 for more information, especially if it looks cloudy. The next meeting is 7pm Wednesday, 6 April, at Pedro Castle.
So clear skies everyone! Mind you, I need to add these days – let’s hope they are dark ones too.
Chris Cooke is a member of the Cayman Islands Astronomy Society.