Telescopes
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"Space telescopes." Technology, Telescopes, Q-files Encyclopedia, 8 Nov. 2023.
https://www.q-files.com/technology/telescopes/space-telescopes.
Accessed 19 Mar. 2024.
Space telescopes 2023. Technology, Telescopes. Retrieved 19 March 2024, from
https://www.q-files.com/technology/telescopes/space-telescopes
Technology, Telescopes, s.v. "Space telescopes," accessed March 19, 2024.
https://www.q-files.com/technology/telescopes/space-telescopes
Space telescopes
The Earth’s atmosphere stops many types of radiation from reaching the surface. To study these sorts of radiation, space telescopes stationed in Earth orbit must be used instead. These telescopes have special mirrors to reflect and focus the radiation, and electronic detectors to record the images formed, which are radioed back to Earth. Optical telescopes also benefit from being in orbit because the atmosphere distorts light rays as they pass through it. The Hubble Space Telescope has sent back many detailed images of stars, galaxies and nebulae that were not possible to obtain before. Its successor, the James Webb Space Telescope, is searching for the most distant galaxies in the observable Universe.
Updated 8th November 2023
Hubble Space Telescope
Orbiting 559 kilometres (347 miles) above Earth is the Hubble Space Telescope (HST), launched by the Space Shuttle in 1990. It can detect visible light, infrared and ultraviolet rays. It has special mirrors to reflect and focus images and electronic detectors to record them. Images are sent to Earth via the telescope’s antennae. It is so sensitive it could detect light from a torch 400,000 kilometres (250,000 miles) away.
Images from
the Hubble
Scientists can point the Hubble towards any part of space and receive clear pictures of distant stars that are far better than any taken from Earth. This is because Earth-based telescopes have heat, cloud and other disturbances in the atmosphere to contend with. Because of this, more distant stars appear faint or blurred, even if observatories are sited (as many are) on mountaintops far away from city lights and smog.
Inside the Hubble
Like most modern large telescopes, the Hubble is a reflector: it uses mirrors to focus an image of the stars or galaxies it is pointed towards. The main mirror reflects light from distant stars and galaxies on to the secondary mirror. This focuses the light down through a central tube to sensors. Images can be transmitted down to Earth using the antennae. Computers are used to redirect the telescope. Solar panels turn sunlight into electric power for the telescope.
Kepler
Kepler was a space telescope launched by NASA in 2009 to discover Earth-size planets orbiting other stars, known as exoplanets. Named after astronomer Johannes Kepler, it searched for planets in stars' habitable zones. Kepler was equipped with a 1.4-metre (55-inch) primary mirror and a photometer, which monitored the brightness of over 145,000 stars. Astronomers look for any dimming caused by exoplanets that cross in front of their host star. During its service Kepler found more than 2300 exoplanets. In October 2018 it ran out of fuel needed for operations, and is no longer in use.
James Webb
Space Telescope
The James Webb Space Telescope (JWST) is the successor to the Hubble Space Telescope. It orbits the Sun much farther out from Earth's orbit, around 1.5 million kilometres (940,000 miles) from Earth, at a point (L2 Lagrange point) where it is always in the shadow of the Earth. Launched on 25th December 2021, the JWST has a primary mirror measuring 6.5 metres (21.6 feet) at its widest point. It is made up of 18 hexagonal mirror segments covered in a thin layer of gold. The JWST is mainly used to detect infrared radiation.
Euclid
The Euclid Space Telescope, launched in 2023, is to investigate dark energy and dark matter. Dark energy is the name given to a mysterious force that has been shown to be accelerating the expansion of the Universe, and of which the majority (68%) of the Universe is composed. Euclid will measure the distances to millions of galaxies and look at how they are distributed through space. Scientists want to know whether the rate of expansion over the past 10 billion years has been constant or varied. The answer will reveal more about dark energy.
Dark matter is a form of matter that cannot be seen directly, probably because it is made up of particles that do not emit, reflect or absorb light. It acts as a kind of cosmic "glue" which holds galaxies together. Up until now, astronomers have only been able to infer the existence of dark matter by observing its effect on the behaviour of galaxies.
An optical telescope named after the ancient Greek mathematician, Euclid will be positioned at the second Lagrange point 1.5 million kilometres from Earth. At this location, shared with the Webb telescope, it will be pointing away from our planet, but shielded from the Sun's rays by it.
Scientists will use the phenomenon known as gravitational lensing to build a highly detailed 3D map of the heavens. This involves Euclid gathering millions of images of very distant objects, whose light will have passed through dark matter on its way to the space telescope's 1.2-metre-diameter primary mirror. The dark matter causes the light to stretch and bend. The distorted images this produces will tell scientists more about the nature of dark matter.
Consultant: Mike Goldsmith