In the final Research Article for 2015, Dr. Neil Trappe, Senior Lecturer in Experimental Physics in  Maynooth University  writes about how his research helps scientists ‘see’ much more of the universe than previously possible.

Starsinthesky
Stars in the sky (Image credit ESA/Hubble)

Background

When you look outside at the clear night sky you will see many thousands of stars overheard which is, of course, a beautiful sight. The Moon, stars, planets, comets and galaxies can all be observed if you know where to look just using your eyes. But if you have a pair of binoculars or a telescope these optical instruments also you to see much more detail and many fainter objects you would not be able to see with just your eyes. The telescope gathers more light and magnifies the objects letting you see more and enhance your view.

Astronomers spend many hours looking at the night sky with large automated telescopes from many exotic places around the world to add to our knowledge of the Universe and understand difficult questions like how did the Sun and our Solar System form, how are stars born and how do they die, is there life elsewhere in the Universe, and indeed how did the Universe come into existence at all?

In Maynooth University a team of researchers develop telescopes to see the Universe with different kinds of light, specifically far infrared and microwave light. As we discuss below, light that we see with our eyes is only a small part of the light or electromagnetic radiation released by astronomical objects. Why do they do this at all you might ask, why do you not just observe with normal light that we see with our eyes? Well, the answer is we see the Universe differently and can learn lots more information ‘seeing’ with light that is invisible to our eyes.

The Electromagnetic (EM) Spectrum

Electromagnetic spectrum
The entire electromagnetic spectrum is much more than just visible light. It covers of range of wavelengths of energy that our human eyes simply can’t see. (Image credit: NASA)

When you think of light we all refer to our experience of seeing with our eyes. Interestingly when we see different colours of light (e.g. a rainbow) we are actually detecting different frequencies or wavelengths of light. The human eye can only see over a wavelength range from only from blue to red light, but other ‘light’ or EM radiation exists much further either side of the visible part of the spectrum also as is shown in the diagram below taken from the NASA website.

The electromagnetic spectrum is the term used by scientists to describe the entire range of light that exists. From radio waves with low energies to very energetic gamma rays, most of the light made by astronomical sources in the universe is completely invisible to us!

Different light = different information

So astronomers use the entire EM spectrum to observe a variety of different objects in the Universe. Depending on the source conditions more of less of the different types of radiation is produced. In general colder objects are less energetic and produce light in the radio end of the spectrum while hotter more energetic sources or events produce more x ray and gamma ray radiation. If we only study the Universe with visible light we only see objects that produce a lot of visible light (such as stars) and we miss many important objects completely and this is why we try to use all wavelengths or frequencies of light to see the full picture of what’s out there!

orion nebula
The Orion nebula: a region where stars are formed from gas clouds. (Image credit: ESA/Herschel)

Now at Maynooth University a group of researchers design, model and help build telescopes that are sensitive to infrared and microwave light – the longest wavelengths and lowest energy of light which is really good to see inside dense interstellar clouds and track the motion of cold, dark gas – the stuff that stars are made from. So for astronomers to understand how stars form, we really need to observe these large clouds of gas with microwave telescopes. We simply can’t see this happening with optical telescopes because the light is blocked – the same way you can’t see the stars when it is cloudy at night!

A picture of one of these star forming regions is shown above and is in the constellation of Orion, (called the Orion nebula which is also visible with the naked eye) and is one of the closest star forming regions to us here on Earth where we believe many stars are currently starting out.

Ireland is part of the European Space Agency (ESA), which proposed to build a telescope called The Herschel Space Observatory dedicated to seeing this microwave light. It is the largest science satellite to be launched and was launched in May 2009 to see the cold Universe. The mission was a great success and many new discoveries were made that scientists could not see with other telescopes including seeing lots of really complex molecules in the gas between stars which may have helped start to form life on Earth.

The Herschel Space Observatory (Image credit: ESA)
The Herschel Space Observatory (Image credit: ESA)

Maynooth University was involved in the optical design and testing of this telescope representing Ireland and have helped to make many marvellous new discoveries. Much more details of this mission can be found at http://sci.esa.int/herschel/ and if you are interested in the research carried out in Maynooth have a look at our website at https://www.maynoothuniversity.ie/experimental-physics/our-research

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