What was the bright object I saw in the sky last night? Is it a star, is it a planet or is it a plane? A handy guide to identifying that bright object you saw last night. Planets Venus © Paul Smith, Astronomy Photographer of the Year Young Commended 2009 The chances are it’s Jupiter or Venus (or just occasionally Mars). Planets will appear to move across the sky as the Earth turns, keeping their position with respect to the surrounding stars. Unlike stars, they generally don’t twinkle as they have an apparent diameter large enough that the effect of turbulence in the Earth’s atmosphere averages out. Jupiter and Venus can both be strikingly bright. At maximum brightness Jupiter is four times and Venus 19 times as brilliant as Sirius, the next brightest star after the Sun. Once every 17 years Mars can be as bright as Jupiter (the last time was in 2003). Stars Man Looking Up at Stars © Ben Canales, Astronomy Photographer of the Year People and Space Runner Up 2013 If the object you saw twinkled (possibly appearing to change colour as it does so) then it was probably a star. For example, in winter in Britain Sirius is visible fairly low in the south and shows exactly this behaviour. Aeroplanes and satellites Closer to home, if an aeroplane is flying directly towards you, it can appear to be stationary for a while (although the flashing landing lights may be visible) and can also be confused with a star or planet. However at some point the aircraft will appear to veer sideways or upwards as it passes by. Many artificial satellites are also visible to the unaided eye and can be brighter than many stars. Satellites typically take about two minutes to cross the sky from one horizon to another. They are silent and do not have flashing lights. They fade out if they enter the Earth’s shadow. Comets, meteors and meteorites Comet Holmes © Nick Howes, Astronomy Photographer of the Year Our Solar System Commended 2009 Although visible comets with their spectacular tails, are quite rare and you would be wise to look up the next expected visit, they do leave a large quantity of space debris in their wake. When the Earth passes through these debris fields, we see meteors or shooting stars as these bits of dust burn up in our atmosphere. Occasionally a larger object smashes through the atmosphere and hits the Earth. This is a meteorite and will have come from an asteroid. UFOs Disappointingly, perhaps, UFOs don’t exist. Or do they? The truth is out there. Accessible astronomy guides Let our practical astronomy guides, approved by Royal Observatory astronomers, help you navigate the night sky. Shop Planisphere & 2023 Guide to the Night Sky Britain and Ireland Book Set £18.00 The perfect companions for a night of stargazing. Available for the special price of £18.00 when purchased together. The Planisphere is an easy-to-use practical tool helps any astronomers identify the constellations and stars for every day of the year... Buy Now Shop Royal Observatory Greenwich Illuminates Astronomy Guides Set of 2 from £18.00 Special Price. Save £1.98 when you purchase two astronomy titles from the Royal Observatory Greenwich Illuminates guides together... Buy Now Shop Royal Observatory Greenwich FirstScope 76 Celestron Telescope £89.99 It doesn’t get much simpler or more portable than the Celestron FirstScope’s tabletop Dobsonian design. Just remove it from the box, insert an eyepiece, and you’re ready to view the Moon, planets, nebulae, and more! This high quality Dobsonian style stand with its 76 mm reflector optical tube make the FirstScope an ideal entry level astronomical telescope... Buy Now