Sat, 25 Mar 2017
Your sky during Earth Hour
Tonight, 25 March 2017, from 8.30 pm to 9.30 pm, is Earth Hour. This internationally recognised event is when many public buildings and householders will switch off their lights to show support for efforts to control climate change, which is believed by most scientists to be caused in part by increased carbon emissions.
As well as demonstrating support for this effort, Earth Hour will inspire people to go out and look at the sky – hopefully less illuminated by upward-pointing floodlights which are a major contributor to light pollution.
So what stars will you be able to see during Earth Hour? Here’s our map for the sky as seen from the UK at 8.30 pm tonight.
You might think that we have the points of the compass all wrong. But this is a map of the sky, so you have to hold it over your head. This where a tablet comes in handy! When you do this, east and west will be the right way round.
It shows the whole sky, so the scale is quite small. Normally you turn to see different parts of it, so to see the view looking north, for example, hold the map above you with north at the bottom.
To start finding your way around, first pick out an easily recognised star pattern and work from there. Tonight, the brightest constellation of all, Orion, is on view, in the south-west. Its three stars in a line are visible through the worst light pollution. Or if you can’t see in that direction, look above you and you’ll see the bright star Capella, one of the brightest in the sky, almost overhead.
Not far from Capella is a pair of bright stars, Castor and Pollux, also known as the Heavenly Twins or Gemini. Or look north to find The Plough, or the W-shape of Cassiopeia.
Once you’ve found these stars you can go on to pick out more of the constellations and even locate the planet Mars. Later in the evening, Jupiter will be rising in the eastern sky, outshining all the stars.
You won’t see the Moon, though, as right now it’s only visible as a thin crescent in the early morning sky before dawn.
Want to see a map with more stars labelled? Use our interactive map, which you can adjust to show the sky for any date and time. It's set for 10 pm on 15 March. but you can change the time as shown in the caption under the map.
If this has got you interested and you want to know more, think about joining the Society for Popular Astronomy. Right now the annual subscription is £20 a year, and there are special rates for those under 18. Find out what we do and watch a video from Professor Brian Cox here.
Added by: Robin Scagell