{"id":58703,"date":"2024-05-08T10:45:24","date_gmt":"2024-05-08T10:45:24","guid":{"rendered":"http:\/\/290ac4b8-fd08-4686-8e89-73170daf85dd"},"modified":"2024-05-08T11:08:25","modified_gmt":"2024-05-08T11:08:25","slug":"observing-the-invisible-how-astronomers-use-the-electromagnetic-spectrum-to-explore-the-universe","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/observing-the-invisible-how-astronomers-use-the-electromagnetic-spectrum-to-explore-the-universe\/","title":{"rendered":"Observing the invisible. How astronomers use the electromagnetic spectrum to explore the Universe"},"content":{"rendered":"

We can learn so much more about space and the Universe by observing objects in wavelengths other than optical light. <\/p>

By <\/p>

Published: Wednesday, 08 May 2024 at 10:45 AM<\/p>

\n\n

Electromagnetic waves are a form of energy that have both an electric and magnetic component.<\/p>

They\u2019re different from mechanical waves since they\u2019re one of the only things that can propagate long distances through the vacuum of space.<\/p>

A Webb \/ Hubble combined view of the Phantom Galaxy, M74, in optical and infrared. Credit: ESA\/Webb, NASA & CSA, J. Lee and the PHANGS-JWST Team; ESA\/Hubble & NASA, R. Chandar \/ Acknowledgement: J. Schmidt<\/figcaption><\/figure>

And as we are surrounded by that vacuum, if we want to see what is out there we are currently reliant on the electromagnetic spectrum.<\/p>

I have spent much of my career working in different parts of the electromagnetic spectrum<\/a>.<\/p>

My trip with the light fantastic began where it begins for most, with visible light and the \u2018mark one eyeball\u2019.<\/p>

I began looking up at the night sky at an early age and wanted to enhance my view, so I built my own telescope to gather more light than I could with just my eyes.<\/p>

\"James
James Webb Space Telescope image of part of the Milky Way\u2019s core in infrared. Credit: NASA, ESA, CSA, STScI, and S. Crowe (University of Virginia).<\/figcaption><\/figure>

This started me in a career in instrumentation, and as well as visible light I have used radio waves, infrared<\/a> and ultraviolet to understand our surroundings, both here on Earth and out in space.<\/p>

As some electromagnetic wavelengths are absorbed by our atmosphere we need to get above it to capture them, so we build space instrumentation.<\/p>

But in astronomy what do we gain by looking at the various parts of the spectrum?<\/p>

\"A
A view of the Whirlpool Galaxy in optical light (white) and radio waves (red). Credit: NRAO\/AUI\/NSF; HST composite by B. Saxton<\/figcaption><\/figure>

Different types of electromagnetic radiation are generated by specific types of interaction between matter.<\/p>

At the low energy end, radio waves are generated by the twisting and spinning of molecules: the Whirlpool Galaxy<\/a> observed through a radio telescope reveals areas of cool gases such a carbon dioxide.<\/p>

Moving up in energy we get infrared waves, which are caused by the collision of atoms and the exchange of electrons.<\/p>

This reveals areas of the Whirlpool Galaxy where small, cool, red stars reside and these make up the majority of the galaxy.<\/p>

\"Hubble
Hubble Space Telescope’s infrared view of galaxy M51, the Whirlpool Galaxy. Credit:NASA,ESA, M. Regan and B. Whitmore (STScI) and R. Chandar (University of Toledo, USA)<\/figcaption><\/figure>

Up the energy again and we get to visible light, this is caused by the movement of electrons within an atom, which causes the absorption and emission of photons.<\/p>

This part of the spectrum reveals stars not too dissimilar our own Sun in M51.<\/p>

Now we come to the higher energy areas of the spectrum: ultraviolet, X-rays and gamma rays.<\/p>

Ultraviolet waves show M51\u2019s larger, hot blue stars, their energy generated by ionised gases where free electrons can exist. X-rays show us the hot areas of galaxies.<\/p>

\"A
A GALEX ultraviolet image of the Whirlpool Galaxy. Credit: NASA\/JPL-Caltech<\/figcaption><\/figure>

Observing in these energies elsewhere reveals the locations of things like black holes, neutron stars and binary star systems, which all emit X-rays.<\/p>

At the top end of the light fantastic we get gamma rays, highly energetic waves that are produced by radioactive atoms and nuclear explosions.<\/p>

Supernovae<\/a>, neutron stars<\/a>, pulsars<\/a> and black<\/a> holes are all sources of celestial gamma rays.<\/p>

It is only by looking at the combination of these different energies that we can get a true understanding of a galaxy that sits some 23 million lightyears away from us.<\/p>

This article originally appeared in the July 2016 issue of <\/strong><\/em>BBC Sky at Night Magazine<\/strong>.<\/strong><\/em><\/p> <\/body><\/html>\n

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