
Telescopes on the Moon
Season 3 Episode 20 | 9m 11sVideo has Closed Captions
Find out about China’s current telescope on the moon.
Find out about China’s current telescope on the moon and what the future plans are for mounting larger telescopes on the lunar surface.
Problems playing video? | Closed Captioning Feedback
Problems playing video? | Closed Captioning Feedback

Telescopes on the Moon
Season 3 Episode 20 | 9m 11sVideo has Closed Captions
Find out about China’s current telescope on the moon and what the future plans are for mounting larger telescopes on the lunar surface.
Problems playing video? | Closed Captioning Feedback
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Learn Moreabout PBS online sponsorshiptelescopes have come a long way since Galileo first fixed two lenses to a tube and discovered the moons of Jupiter in the phases of Venus but the telescope's are tomorrow we'll continue this advance and allow us to crack open some of the greatest mysteries of the universe the Hubble Space Telescope is the most important Observatory ever built it's stunning images and spectra have opened up incredible windows on our universe but Hubble was launched in 1990 and is still working hard over a decade past its original 15 year design life it's time for the next generation of great observatories first up is the Hubble Space Telescope's much-publicised successor the James Webb Space Telescope with a diameter of 6.5 meters compared to Hubble's 2.4 it has over five times Hubble's collecting area that means vastly greater sensitivity as the largest telescope ever scheduled for launch the only way to fit it into the rocket is to fold it origami style Webb will begin unfolding its 18 hexagonal mirrors on its journey to the Sun earth systems second Lagrange point about a million miles away it will continue unfolding cooling and testing forever five months before opening its cameras to the sky these cameras see mostly at infrared wavelengths of light unlike Hubble's which are optimized for visible and ultraviolet light why infrared baby pictures lots of them deep in debris and deep in the past two planets form around young stars and young stars like tucked away in blankets of gas and dust longer wavelengths of light scatter less easily than shorter wavelengths and so have an easier time escaping these dust packed stellar nurseries compared to shots from Hubble this taken invisible wavelengths this in infrared Webb will see even longer wavelength infrared light and so will bore even deeper Webb's larger mirror allows to detect objects sixteen times fainter than Hubble this will provide another set of baby pictures the formation of the very first stars and galaxies in our universe for these Webb sensitivity and infrared capability a birth critical like from these earliest of galaxies has been traveling through our expanding universe near the beginning of time that light has been stretched out by that expansion deep into the infrared web may detect objects at a cosmic age of just a hundred million years far earlier than currently possible Webb will help us learn whether stars form galaxies or galaxies form stars and the role of dark matter in the whole process using infrared light is a double-edged sword because light has a dual nature it can gather off a dust grain like a particle and it can also be deflected by the edges of our telescope like a wave in a process called diffraction as a result there's an absolute limit in how sharply light can be focused a single point like a star will always be a little bit blurred when it reaches our camera the finest detail any telescope can observe is given by the diffraction limit which increases with wavelengths this means that infrared has a disadvantage over visible or ultraviolet light however the diffraction limit gets smaller with increasing aperture size what web losses due to concentrating on the infrared it makes up through sheer size it's infrared pix will be just as clear as Hubble's visible light images the biggest challenge at observing infrared wavelengths is heat space is good for that because the heat glow of the atmosphere is so bright but uncooled telescope electronics are even brighter when the detectors will be cooled with cryogenics to a frigid 50 Kelvin or minus 223 degrees Celsius it also sports a five layer Sun shield to block as much sunlight as possible this fragile structure has the added benefit of blocking small space debris Webb will pick up Hubble's legacy but without sensitivity to visible or ultraviolet wavelengths it will not replace Hubble the true successor to Hubble will not be in space at all a new generation of ground-based extremely large telescopes is being planned the first will be the giant Magellan telescope currently under construction in the other Kama desert region of the Chilean Andes GMT comprises seven enormous monolithic mirrors each weighing about 15 tonnes see that they provide an effective aperture 24.5 meters in diameter and a collecting area over 80 times Hubble's and nearly 15 times Webb's however using telescopes within the Earth's atmosphere comes with complications observing in infrared wavelengths is hard that GMT is built to explore visible wavelengths just like Hubble then there's the issue of astronomical scene those are supremely dry air above the Atacama Desert gives us some of the best astronomical observing in the world even that air is in constant motion we can think of light from a very distant point like object say a star as reaching us as a series of wave fronts our eyes now telescopes can focus those wave fronts back into a point with perfect focus we can reconstruct every point on the sky creating a perfect image the turbulence in the atmosphere walks those wave fronts to our eyes this is what causes stars to twinkle for telescopes it blurs the crisp diffraction-limited image of seen in space this scene or size of the blurring increases if we built GMT is giant mirror interspace it would produce images 10 times sharper than Hubble's underground that resolution is normally limited to about 10 times worse than doubles but these days the most advanced ground-based telescopes can actually correct for Atmospheric blurring with a technique called adaptive optics GMTs depth of optics will be next levels its secondary mirrors will be flexible deformable at high speed by thousands of computer control actuators to correct the walkway frames in order to track this turbulence in real time GMT will shine six powerful sodium lasers 90 kilometres into the upper atmosphere where their light will produce artificial guide stars its mirrors will deform up to hundreds of times per second to keep the guide stars along with everything else on the telescope's sight in sharp focus with this technology GMT will be able to get close to the diffraction limited resolution promised by its enormous aperture GMTs extreme sensitivity and unprecedented sharpness will actually allow to take photographs of planets in other solar systems and even to observe the spectra of the atmospheres of some planets it hopes that GMT will even find traces of the very first population of stars that formed in our universe also in Chile will be a new type of telescope we have never seen before the large synoptic survey telescope primary mirror spans eight point four meters three and a half times larger than Hubble's but LSST secret lies not so much in size as its incredible speed LSST will scan the whole southern sky every few nights it is possible because of the giant field of view of its car-sized 3.2 gigapixel camera in a way LSST focuses more on the dimension of time rather than spaced it will see how things in our universe move and change over days months and years by comparison the Sloan Digital Sky Survey maps large fractions of the sky over an entire year LSST is hundreds of times faster every night for 10 years it will take 1000 pairs of exposures and store 15 terabytes of data we will be able to track the motion of rogue high velocity stars whizzing through our galaxy will spot countless fast-moving objects in our own solar system including potentially hazardous asteroids that could one day impact the earth it will be easier to find new supernovae the explosive deaths of stars which among other things will improve our understanding of dark energy also catch the visible light counterparts to gamma-ray bursts the most energy explosions in the universe will record the twinkling of objects in the distant universe as their brightness has fluctuate due to the change in gravitational effect of nearby massive bodies this will allow us to map the universe using gravity itself as a lens the Webb GMT and LSST will change the way we do astronomy they are designed to tackle some of the biggest questions about our universe known unknowns however it's likely that their most exciting revelations will be things we didn't even expect to find unknown unknowns in the deepest reaches of
- Science and Nature
A series about fails in history that have resulted in major discoveries and inventions.
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