UNITED STATES: Although Webb is frequently referred to as Hubble’s replacement, NASA prefers to refer to it as a ‘successor’. Being Hubble’s scientific successor, Webb’s scientific objectives were inspired by Hubble’s findings. To “go beyond” what Hubble has already accomplished, Hubble’s science has forced us to look at longer wavelengths.
The light from farther away objects is pushed from the UV and optical into the near-infrared because they are more highly redshifted. Therefore, an infrared telescope is needed to observe these far-off objects, such as the first galaxies formed in the universe.
Since its capabilities differ from those of Hubble, Webb cannot replace it. While Hubble examines the universe largely at optical and ultraviolet wavelengths, Webb will primarily observe it in the infrared (though it has some infrared capability). Webb also has a far more oversized mirror than Hubble. Webb can see further into the past than Hubble because of its greater light-collecting area.
At the second Lagrange (L2) point, Webb will be 1.5 million kilometres (km) from the Earth, whilst Hubble is in a relatively close orbit.
Overall Size Comparison between the two telescopes
Mirror size comparison
Compared to the mirrors available on the current generation of space telescopes, Webb’s primary mirror has a diameter of about 6.5 metres, giving it a substantially bigger collecting area.
Webb has an almost 6.25 times larger collecting area than Hubble because of Hubble’s mirror’s significantly smaller 2.4-metre diameter and 4.5 m2 comparable collecting area! Compared to Hubble’s NICMOS camera, Webb’s field of view is around 15 times greater, and its spatial resolution is about 100 times higher than Spitzer’s infrared counterpart.
The distance between the Earth and the Sun is 150 million kilometres, and the Moon travels at a distance of 384,500 kilometres around the Earth. Hubble, on the other hand, is 570 km far from Earth. Webb doesn’t orbit the Earth; instead, it is 1.5 million kilometres away at the L2 Lagrange point.
Webb’s solar shield will block the Sun, Earth, and Moon’s light at the L2 point. This will assist Webb in maintaining its cooling, which is crucial for an infrared telescope.
According to the image above, Webb orbits the Sun in a clamp with the Earth while being fixed in the exact location of both bodies. As you can see in the picture, satellites actually circle around the L2 point; they don’t remain static at a single location.
A file interactive tool made by John Christensen has given this context to thousands of individuals on Reddit and Twitter. By lining up photos produced by the Hubble Space Telescope with Webb Telescope, the web tool enables users to instantly compare them side by side.