A new view of deep space
Scientists have released the first images taken by the telescope with the most ambitious mission in history. The James Webb Space Telescope (JWST) is a joint project of the US space agency, NASA, the European Space Agency and the Canadian Space Agency. After 30 years of planning, construction and testing, it was launched on Christmas Day
2021 into an orbit about a million miles from Earth. JWST’s huge light-collecting mirror, which is 6.5 metres across, is so big that it had to be split into 18 hexagonal segments and folded up for launch. Over the following months, these segments had to be slowly unfolded in space before its cameras and other instruments could start collecting data.
The very first JWST image was revealed by US president Joe Biden on 11 July. It shows a distant group of galaxies known as the SMACS 0723 cluster. The galaxies appear in the image as bright balls and ovals. They are so far away that their light has taken 4.6 billion years to reach us. This means that JWST’s image shows the cluster as it was in the distant past. However, scientists are just as interested in light from even more distant and fainter galaxies, which appear in the background. Shown in redder colours in the image, the light from some of these galaxies has taken 12 billion years to reach us. The Big Bang explosion that created the universe happened about 13.8 billion years ago, so JWST’s image shows these galaxies when they were very young. The image covers an area of sky that is only about the size of one grain of sand if it was held at arm’s length by someone looking from Earth – so imagine how many galaxies there are in the whole universe!
Other JWST images show objects closer to home in great detail, such as an egg-shaped gas cloud called the “Southern Ring Nebula”. This was blown out like a bubble from the surface of a dying star. Images also show the Carina Nebula, where new stars are being born, and heat escaping from the clouds of planet Jupiter.