Physics and Astronomy

Infrared Photos

Learn about infrared astronomy and collect your thermal infrared photos!

This page contains an introduction to infrared light, infrared astronomy, the JWST, and allows you to collect your thermal/infrared photographs taken at one of our many public events!

What is infrared light?

Thermal Infrared photograph of visitors to Stargazing Live 2017

Light is made up of tiny packets of energy called photons, which are emited by electrons around atoms. These photons can be emitted with different amounts of energy, and we see that as colour. So blue light is made up of photons with more energy than photons of red light.

While we see between red and blue light with our own eyes, there are types of light beyond this that we cannot actually see. Light beyond the red end of the visible spectrum is called infra-red light, and beyond the blue end we have ultra-violet, X-ray and gamma-ray light.

It's a shame that we can't see beyond red and blue light with our own eyes, but we can see beyond red and blue with very specialised cameras, that detect these invisible forms of light and converts them into light that we can actually see! And that is what our thermal camera does. The montage to the right shows infrared photographs of visitors to our Stargazing Live 2017 event.

In addition, as shown by the thermometer below, gas at different temperatures emit light at different colours or even different types of light. A hot star at 40,000oC will emit mainly blue light. The Sun is at around 6,000oC and so emits mainly yellow light. Cool stars at 4,000o appear red, while even cooler stars (such as baby stars, that have recently formed and so are still quite cool) emit mainly infrared light.

The full electromagnetic spectrum as a thermometer
Why do astronomers use Infrared light?

To understand our universe, astronomers don't only look at the visible light that we can see with our own eyes, they also observe light at different wavelengths: radio waves, infrared, optical, ultra-violet, X-rays and Gamma-rays.The galaxy Messier 82, the closest example of a “starburst galaxy”, seen by NASA’s Spitzer satellite. Image: NASA/JPL-Caltech.

Objects at different temperatures emit light at different wavelengths. Cool objects below 2,000oC, like ourselves, are not hot enough to emit visible light - we emit infrared light. Stars at 3,000oC mostly emit red light, while blue stars are glowing at 40,000oC. Much hotter objects, can emit ultra-violet, X-rays or even Gamma rays!

At the University of Sussex, we carry out research in Infrared Astronomy - looking at cool stars in our galaxy, at dusty star-forming regions (dust blocks visible light, but infrared light can still pass through), and also distant galaxies (whose light has been redshifted so much, we see them emitting infrared light).

Below, you can see photographs of the Andromeda Galaxy in visible light (left; by astrophotographer Robert Gendler) and in infrared light (right; taken by the European Herschel Space Telescope). The Herschel Space Telescope allows us to see where stars are forming, by the infrared light that these cool, dusty star-forming regions emit. More information about these images is at the European Space Agency website.

Find out more about what we do in the Department of Physics & Astronomy at our research pages.

The Andromeda galaxy, as seen in visible light The Andromeda galaxy, as seen in infrared light
What is the James Webb Space Telescope?
Thermal Infrared photograph of visitors to Stargazing Live 2017

The James Webb Space Telescope is an infrared space telescope that is the successor to the Hubble Space Telescope. It is being built by an international collaboration that is being lead by ESA in Europe and NASA in the USA.

Astronomers at the University of Sussex's Astronomy Group will be using the JWST once launched in 2020, and we are currently planning how to make best use of the telescope, and what targets to observe.

Further information about JWST can be found at NASA, at ESA, and on the Wikipedia.

How do you look in infrared light? Collect your photos!

Please Note: Images from the University of Sussex Community Day are now available!