Introduction to Astronomy

I’m Dr. Tom Stallard, and I’m an astronomer in London, England. I study the biggest planets in the solar system, Jupiter, Saturn, Uranus and Neptune. These are often called the Gas Giants, because unlike Earth, they have no solid surface, so that you could not stand on them, you’d just fall down and down… I look at the very top layer of these planets, where the gas is very thin; it is so thin that only the two lightest types of gas exist, Hydrogen and Helium. I study the way these gases glow when particles from space crash into them. The gas giants have a magnetic north and south pole, just like the Earth, and particles called ions are steered towards these poles from space. On Earth, when these particles hit the atmosphere, they also make the oxygen in the sky light up – this is what causes the Northern Lights, also known as the Aurora Borealis. So I study the aurora on other planets.

Of course, the gas giants are a very long way away. Jupiter is the closest to Earth, but it is at least four times as far away as the Sun is. Saturn is at least twice as far away as Jupiter, Uranus is twice as far again, and Neptune is double that! This means that if I want to see anything on these planets, I have to use a big telescope in order to see them properly. Most people think of telescopes as long thin tubes that you look through, but the telescopes that I have to use are so big that they have to be made in special ways. Because of that, rather than looking though an eyepiece, I use a special computer chip that reads in the light, and puts it onto a computer monitor. I do all my work at a computer, so I never actually get to see the planets with my own eyes.

I do have to travel out to the telescope, though. The best telescopes in the world are in Hawaii, so I have to fly from London, across America (stopping in San Francisco), all the way to the Big Island of Hawaii – a journey that takes almost two days. Once I’m there, I have to drive up a mountain called Mauna Kea (which means the White Mountain in Hawaiian), from the sunny town of Hilo. We sleep half way up at some specially built dormitories, and then every night we drive to the summit, 14,000 feet high. That high up, it is cold, and the air is so thin that you can get dizzy from lack of oxygen. We get to stay in the warm offices around the telescope, and work on the computers there, but if we go outside, it’s as cold as the winter weather, close to freezing, so I have to pack lots of winter clothes – not many people do that when they fly to Hawaii!

There are lots of different types of big telescopes, designed to look at different kinds of light. The light we see with our eyes can be split up into different colours, which is what makes a rainbow. The red in the rainbow is a different energy to the blue in the rainbow. There are many other kinds of light that have widely varying energy. It might sound strange, but X-rays are a form of high energy light, and radio-waves are a form of low energy light, and there are telescopes that look for all these kinds of light in the sky. The telescope I use, the NASA Infrared Telescope Facility, looks at a kind of light called infrared. Infrared is the same as heat, so even heat is a type of light. We split the infrared light up, like raindrops split up visible light in a rainbow. This means we can measure the light very exactly. Most of the other telescopes on Mauna Kea also measure either infrared or visible light, but there are also telescopes that measure radio waves.

On top of the mountain, you can watch the sun set beneath you, since the clouds are nearly always far below you. You can often see the other mountains of Hawaii peeking above the clouds. It is very exciting to be working at the telescope, but it can also be very boring at the same time, since you have to work all night on twelve hour shifts. During most of that time, I just sit and stare at the computer screens. To take an image of the planet, I only have to press a button, and the telescope automatically records the information into the computer for me, so it can often get very repetitive.

I don’t get to use the telescopes very often, since there is a lot of demand to use them from all the other astronomers in the world, so most of my work is done back in London. I work in an office, and analyse the data that I take. If we find anything new, we write up the results and publish them in scientific journals, so that everyone else can know what we have discovered. Being an astronomer is an amazing job. You have almost complete control over what you are doing, from proposing an idea, through making observations and recording your results, to writing up, editing and publishing your findings. I like doing all of this, but the most rewarding part has to be travelling to Hawaii, and getting to use the big telescopes there.




A general description of the work I do, written ages ago

solar wind

A diagram of the solar wind, as a basic overview of how it is that planets have aurora


An animation of Jupiter, in which both the aurora and red spot can be seen in the near-infrared