Main differences between Hubble and James Webb telescopes

Main differences between Hubble and James Webb telescopes

The James Webb Space Telescope was conceived as a successor to Hubble, all of which are designed, built, tested and ready to be launched on the Ariane V missile. It is not a replacement, but a successor. This is true, first of all, at the scientific level, because its scientific objectives are motivated by the results obtained from Hubble. In fact, it is thanks to Hubble that we have learned how exciting and scientifically significant it can be to travel far away. To a more distant object, to a longer wave. With Hubble, we have filled many fragments in our space vision. James Webb, a telescope that works in infrared range and has great innovations compared to its predecessor, can add much of what we lack.

Together with Hubble, who will continue to give us beautiful images in the visible and ultraviolet range of wave lengths, Webb will allow us to reach even wider wave lengths, which means a longer past and secrets hidden far beyond centuries.

Webb and the infrared universe

The James Webb Space Telescope will conduct observations mainly in the infrared range and will be equipped with scientific instruments covering wave lengths between 0.6 and 28 micrometers. We know that the infrared range in the electromagnetic spectrum ranges from 0.75 to several hundred micrometers. Therefore, it is particularly difficult to collect for long periods if the available area is not large enough and the tools are not suitable. By comparison, the Habble instruments can observe a small portion of the infrared spectrum between 0.8 and 2.5 micrometers.

Infrared observations are particularly important because any dust cloud absorbs visible light and re-produces radiation in the infrared range, which means that young stars with dust disk around them, in which planets can form, display an infrared surplus, and the center of our galaxy also does so, preventing us from fully understanding the structure and formation of the galaxy core.

Exactly because a large collection area means:

  • a much wider field of vision, better spatial resolution.

Webb was designed and constructed using a 6.5-metre-diameter-diameter main mirror, which gives him a much more powerful eye than any other telescope ever launched into space. In comparison, the diameter of Hubble's main mirror is 2.4 metres. In terms of the collection area, Hubble has, of course, gone far with that mirror, but not as far as we expect from Webb.

Other observation point

The Hubble Space Telescope has been in orbit on our planet for more than 30 years at an altitude of about 570 km. Webb will be at the Lagrang L2 point of the Earth-Sun system, 1.5 million kilometres away from Earth. That's why Webb will be launched into space on the Ariane V rocket.

In addition, in the L2 position, Webb's solar shield will allow it to block the light of the Sun, as well as the light reflected from the Earth and the Moon, so it's the best choice to ensure the sustainability of the telescope. Webb will actually be orbiting the Earth, but will always remain at the same point in relation to the Earth and the Sun.

How far will Webb see?

It's important to be able to look very far into space, because the further we look, the further we travel in time. But as we observe and study it, the universe continues to expand, and this expansion seems to be accelerating. This results in the radiation being stretched, because space time is stretched and galaxies are spread. As a result, shorter wave lengths will become longer. And remote objects will become less and less visible at the length of the wave of visible light: in fact, it reaches us in the form of infrared light.

So the fact that James Webb's space telescope will be able to see in the infrared range is particularly useful, it's perfect to go further and further and to get to the very roots of the universe, which is as vast as it is mysterious, and to be our eyes on the light, even the light that we can't see from here.