![]() ![]() If Webb is orbiting the Sun further out than Earth, shouldn't it take more than a year to orbit the Sun? Normally yes, but the balance of the combined gravitational pull of the Sun and the Earth at the L2 point means that Webb keeps up with the Earth as it goes around the Sun. This is why L1, L2, and 元 don't "collect" objects like L4 and L5 do. However, L1, L2, and 元 are metastable so objects around these points slowly drift away into their own orbits around the Sun unless they maintain their positions, for example by using small periodic rocket thrust. Some small asteroids are known to be orbiting the Sun-Earth L4 and L5 points. ![]() In fact, L4 and L5 are stable in that objects there will orbit L4 and L5 with no assistance. Some Technical Details: It is easy for an object (like a spacecraft) at one of these five points to stay in place relative to the other two bodies (e.g., the Sun and the Earth). ![]() The L1, L2, and 元 points are all in line with each other - and L4 and L5 are at the points of equilateral triangles. At Lagrange points, the gravitational pull of two large masses precisely equals the centripetal force required for a small object to move with them. Joseph-Louis Lagrange was an 18th century mathematician who found the solution to what is called the “three-body problem.” That is, is there any stable configuration, in which three bodies could orbit each other, yet stay in the same position relative to each other? As it turns out, there are five solutions to this problem - and they are called the five Lagrange points, after their discoverer. This is why the telescope is out at the second Lagrange point. To have the sunshield be effective protection (it gives the telescope the equivalent of SPF one million sunscreen) against the light and heat of the Sun/Earth/Moon, these bodies all have to be located in the same direction. The temperature difference between the hot and cold sides of the telescope is huge - you could almost boil water on the hot side, and freeze nitrogen on the cold side! The telescope itself operates at about 225 degrees below zero Celsius (minus 370 Fahrenheit). We invite you to watch this Hubblecast that explores how Hubble’s observations differ across different wavelengths of the electromagnetic spectrum, and how these observations will be complemented by those of the James Webb Space Telescope.+ The temperature difference between the hot and cold sides of the telescope is huge - you could almost boil water on the hot side, and freeze nitrogen on the cold side! While Hubble is positioned in Earth orbit at an altitude of approximately 570 kilometres, Webb will be orbiting a point in space beyond the orbit of the Moon known as a Lagrange point, roughly 1.5 million kilometres from Earth. Another key difference between Hubble and Webb is where they are located to study the cosmos. Compared to Hubble’s 2.4-metre primary mirror, Webb is equipped with a primary mirror that spans 6.5 metres in diameter. Webb will observe the Universe at wavelengths longer than visible light, namely in the near-infrared and mid-infrared. MIRI is a versatile instrument offering a wide set of modes. It will support the whole range of Webb’s science goals, from observing our own Solar System and other planetary systems, to studying the early Universe. This is made possible by its powerful multi-object spectroscopy mode.ĮSA is also supporting the provision of the MIRI instrument, the only instrument on the telescope that is capable of operating at mid-infrared wavelengths. The primary goal of NIRSpec is to enable large spectroscopic surveys of astronomical objects such as stars or distant galaxies. This includes the NIRSpec instrument, the workhorse near-infrared spectrograph on board Webb, which is provided entirely by ESA. In addition to providing the Ariane 5 rocket and launch services to bring the telescope into space, ESA is also providing instruments for the telescope as well as scientists who will support the mission’s operations. The James Webb Space Telescope is an international project led by NASA in partnership with ESA and the Canadian Space Agency. This includes research on our own Solar System, the formation of stars and planets (including planets outside our Solar System - exoplanets), and on how galaxies are formed and evolve, in ways never before possible. Launched in December 2021 on an Ariane 5 rocket from Europe’s Spaceport in French Guiana, Webb is designed and built to offer scientists the capabilities needed to push the frontiers of knowledge in many areas of astronomy. The James Webb Space Telescope will be the next great space science observatory, designed to answer outstanding questions about the Universe and to make breakthrough discoveries in all fields of astronomy. These visuals feature artist impressions. ![]()
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