19/06/2026
Our next feature is ‘X’ for ‘X-ray Astronomy’. ✨
When you open your eyes to your surroundings, light enters and reaches the retina, which detects light and dark, as well as colour. Your vision is limited though, with most people only able to detect red, green, and blue light, giving them a sense of the colour spectrum, from red to violet. The mix of those colours is what we call white light, and to scientists, it’s the visible spectrum. Your skin, however, can detect ultraviolet, and if it receives too much, you become sunburned. Then there’s infrared, which we feel as heat.
Light is part of the electromagnetic spectrum, which extends from gamma rays to radio waves, and by using different detectors, we can sample each part of the spectrum. Our atmosphere blocks gamma rays, x-rays, and the shorter wavelengths of ultraviolet, but allows visible light and some radio waves to pass through, and in 1932, the first detection of radio waves from space was made, by accident.
In 1948, the first observation of x-rays from the Sun was made, using captured and repurposed German V2 rockets to get above most of the atmosphere, and from the 1960s, satellite observations made it possible to do more widespread investigation of x-ray sources in deep space.
When most of us think of x-rays, we probably think of medical examinations, like looking at broken bones. Astronomers, however, study x-ray sources because the observations provide clues to very energetic processes, such as in very hot environments, or energetic particles being accelerated in a strong magnetic field around a pulsar, as in the Crab Nebula.
Discover more about our galaxy at the Sir Thomas Brisbane Planetarium: https://bnecouncil.cc/4sOcwCY
📸: NASA - National Aeronautics and Space Administration
