Saturn reflecting the Spectrum
Keith's Video Hello 1.8Mb mpg
Hi, my name is Keith Noll. I’m a planetary scientist here at the Space Telescope Science Institute in Baltimore. I am particularly interested in using the HST to find out what the surfaces of Saturn’s and Jupiter’s moons are made of. Even with space probes like Cassini there are still planetary observations that Hubble can do best. It is better for mid UV spectroscopy and it also allows for long term time studies like looking at seasonal changes on the moons. I’m also using the IR NICMOS instrument and the ACS to study Kuiper belt objects.
The image above was captured from a UK back garden with a relatively small telescope – a primary mirror of 20cm. If you’ve never seen Saturn for yourself, try contacting your local astronomy club. Someone there will be happy to let you look through a telescope.
The light that entered the telescope had travelled over a billion kilometres out from the Sun to reach Saturn. It was then reflected off the planet and travelled a billion miles back to Earth. In all, the light had travelled over two billion miles and took two hours to do the journey. In the last 100km of its journey, the light was jiggled about in the Earths turbulent atmosphere. Large chunks of the spectrum were absorbed. It’s amazing that anything is visible at all. Imagine what a telescope with a mirror over 150 times bigger, and above the Earth’s atmosphere can do. That is what you have got with the HST.
Things look a particular colour because they absorb and reflect different parts of the spectrum. For example my mouse mat absorbs most of the spectrum but reflects red light. So we see it as red. HST can see the visible spectrum and parts of the invisible ultraviolet (UV) and infrared (IR) spectrum. Just like this mouse mat is coloured red when seen in the visible spectrum, the substances that make up Saturn’s atmosphere, rings and moons have colours that can be seen by HST in visible and in the UV and IR.
Your challenge is to use HST to find out what Saturn’s rings and atmosphere are made of. Are they water ice, gas or rock? Using filters, you will need to capture images of Saturn in IR, visible and UV bands of the spectrum.
- Water ice is a really good reflector of some wavelengths in the IR but is very good at absorbing some wavelengths in the UV.
- Rock particles are not very good at reflecting visible light.
- Some gases are good absorbers of IR and good reflectors of UV.
Save each image in your work file. Compare the different features that each band has registered.
Now import the images Registax. Adjust the result until you see the greatest amount of detail.
RESULTS
In MS Paint make a key to your image of Saturn. Show which feature reflect and absorb each band of the spectrum.
Click
here to compare your results to ours
