How do you find Saturn in the sky?
As you will know Saturn has rings round it. In many ways finding Saturn is like looking at a ring from the inside. From Earth the planets appear to rotate as if they were in a ring around us. We know that the centre of our Solar System has the Sun with the planets in orbits further and further out.
It takes a year for the earth to orbit the sun but only a day for the earth to rotate once. The planets therefore seem from the earth’s point of view to rotate around us 365 times a year. The orbit of all the planets is flattish relative to the Sun, but the rotation of the earth is slightly inclined. And in the same way that the Sun rises in the sky in an arc and sets at night, so to do the other planets.
In general terms, a planet is going to start being visible low relative to the horizon, climb into the night sky and then set low again.
So we now know that one of the things we are looking for is a light low in the sky moving in an arc like the sun, but at night.
We now have to identify which planet is which in the night sky. We’re on Earth so that only leaves 8 to find or 7 if you agree with the International Astronomical Union that Pluto isn’t a planet and has been reclassified as dwarf planet. Lets go with 7 is it’s less to find. It wasn’t very visible anyway.
First you are going to need a couple of things:
Clothing: If you are going to look at the night sky it’s probably going to be cold. Or at least a different temperature from the day. One of the most spectacular night skies I’ve seen was in the desert of South Australia and I was warm enough in a T-shirt. Possibly you won’t be as lucky. Layers of clothes will work best. If I’m doing something new, I pack everything on the basis that I’d rather be looking at it than looking for it.
Lighting: You are going to need to look at your sky map. Or whatever documentation you use to identify Saturn from the rest of the lights in the sky. A red light is best as this preserves your night vision. These are readily available as small headlight torches with a red facility on eBay.
Due to the pupils of your eyes being wide open for your night vision, do not point any torches directly at each others’ eyes. Some of the newer LED torches are very bright. If you brought someone too stupid to understand that’s a bad idea with you, put them somewhere safe like in the locked trunk of the car.
A map of the night sky: In the old days you used a planisphere. These are basically a couple of disks that you do a bit if alignment to (date and time) and the picture in the middle shows you what the night sky looks like with the relative positions of the stars shown for the date and time. For information about the planets some include a list of the planet positions on the back for a few years ahead. THEY ARE SPECIFIC TO YOUR LATITUDE. So make sure you choose the right one for your geographic location. The advantage of these is you don’t need much else.
Today (welcome to the 21st century) we have computers and specifically netbooks. These little wonders have a massive amount of computing power and last 8 hours on battery. With one of these you can download your sky map program of choice and get a real-time view of where Saturn or any other planet or star is in real time. I am currently using AstroViewer. http://www.astroviewer.com It’s free. With this program you can see when the planets will be visible and with a weather forecast you can get a plan together.
Location Location Location
Pick your viewing spot. Somewhere with an unobstructed view of the horizon if that’s possible. An open-air car park without lights is good. You’ve got a place to park the car and nothing to trip over in the dark. Ideally away from the city lights.
Then ask yourself:
- Which way am I looking?
- Where is Saturn going to appear?
- Is this a good location to view Saturn from?
You’re going to need a compass. At least it is going to make life easier for you. The direction you’re facing isn’t always obvious in the dark.
Just like the Sun, your planet is going to rise in the east and set in the west. Use the constellations you know to lead you to Saturn. I lined up a couple of stars in the Southern Cross to take me to another constellation which saturn was near at the time. There was an extra star in it slightly yellow to the naked eye. That was Saturn on 13th March 2012.
These were taken with a 12 Megapixel EOS550 body connected to an 8″ Newtonian reflector. With that setup Saturn is only 47 pixels across at its widest.
PS: Remember to let the guy in the trunk out at the end of the evening as he’ll be buying the beers.
Have a look at the Moon if you can’t find your way to where is Saturn.
The Moon and photos are here.
© Norman McGeoch, 2012