IMAGING THE ICE GIANTS
Using the latest imaging techniques, Martin Lewis reveals how you too can capture surface details on the most distant planets in the Solar System, Uranus and Neptune
Uranus and Neptune may be the most distant planets in our Solar System but now even amateurs can image them in detail.
Planetary imagers in the UK face tough times over the next few years as Saturn, Jupiter and Mars, all reach opposition well south of the celestial equator. Their apparitions will be short and, as they’ll be relatively low in the sky, the blurring effects of our atmosphere will make much more of an impact. In these lean times distant Uranus and Neptune will remain higher in the sky and an increasing number of imagers will be turning their attention to the different challenges they present.
Although both planets are physically very large, their remoteness means they are angularly very small. Uranus is a diminutive 3.7 arcseconds across – just over twice the diameter of Jupiter’s moon Ganymede – while Neptune is just 2.4 arcseconds in diameter. What’s more, in the outer reaches of the Solar System there’s very little sunlight and so they shine dimly with very low surface brightnesses, compounding the problems of small size.
Despite these difficulties, in recent years amateurs have been able to detect details on these remote worlds using the latest cameras and imaging techniques and by capturing in infrared (IR) light. Although relatively bland in visible wavelengths, when imaged in IR Uranus shows belts, polar features and occasional spots. Neptune is plainer in IR but as its northern hemisphere has moved into summer in recent years large, lighter spots have been tracked by amateurs using larger telescopes. Here we’ll look at how you too can reveal these elusive details in your images of the ice giants.