Our massive James Webb Space Telescope is currently being tested to make sure it can work perfectly at incredibly cold temperatures when itâs in deep space.Â
How cold is it getting and why? Hereâs the whole scoopâŚ
Webbâs giant 6.5-meter diameter primary mirror is part of what gives it superior vision, and itâs coated in gold to optimize it for seeing infrared light. Â
Why do we want to see infrared light?
Lots of stuff in space emits infrared light, so being able to observe it gives us another tool for understanding the universe. For example, sometimes dust obscures the light from objects we want to study â but if we can see the heat they are emitting, we can still âseeâ the objects to study them.
Itâs like if you were to stick your arm inside a garbage bag. You might not be able to see your arm with your eyes â but if you had an infrared camera, it could see the heat of your arm right through the cooler plastic bag.
Credit: NASA/IPAC
With a powerful infrared space telescope, we can see stars and planets forming inside clouds of dust and gas.
We can also see the very first stars and galaxies that formed in the early universe. These objects are so far away thatâŚwell, we havenât actually been able to see them yet. Also, their light has been shifted from visible light to infrared because the universe is expanding, and as the distances between the galaxies stretch, the light from them also stretches towards redder wavelengths.Â
We call this phenomena  âredshift.â  This means that for us, these objects can be quite dim at visible wavelengths, but bright at infrared ones. With a powerful enough infrared telescope, we can see these never-before-seen objects.
We can also study the atmospheres of planets orbiting other stars. Many of the elements and molecules we want to study in planetary atmospheres have characteristic signatures in the infrared.
Because infrared light comes from objects that are warm, in order to detect the super faint heat signals of things that are really, really far away, the telescope itself has to be very cold. How cold does the telescope have to be? Webbâs operating temperature is under 50K (or -370F/-223 C). As a comparison, water freezes at 273K (or 32 F/0 C).
How do we keep the telescope that cold?Â
Because there is no atmosphere in space, as long as you can keep something out of the Sun, it will get very cold. So Webb, as a whole, doesnât need freezers or coolers - instead it has a giant sunshield that keeps it in the shade. (We do have one instrument on Webb that does have a cryocooler because it needs to operate at 7K.)
Also, we have to be careful that no nearby bright things can shine into the telescope â Webb is so sensitive to faint infrared light, that bright light could essentially blind it. The sunshield is able to protect the telescope from the light and heat of the Earth and Moon, as well as the Sun. Â
Out at what we call the Second Lagrange point, where the telescope will orbit the Sun in line with the Earth, the sunshield is able to always block the light from bright objects like the Earth, Sun and Moon.
How do we make sure it all works in space?Â
By lots of testing on the ground before we launch it. Every piece of the telescope was designed to work at the cold temperatures it will operate at in space and was tested in simulated space conditions. The mirrors were tested at cryogenic temperatures after every phase of their manufacturing process.
It will move to Northrop Grumman where it will be mated to the sunshield, as well as the spacecraft bus, which provides support functions like electrical power, attitude control, thermal control, communications, data handling and propulsion to the spacecraft.
Also known as The Sunda flying lemur, it is not actually a lemur and does not fly. Instead, it glides as it leaps among trees. It is strictly arboreal, is active at night, and feeds on soft plant parts such as young leaves, shoots, flowers, and fruits. The Sunda Coluga can be found throughout Southeast Asia in Indonesia, Thailand, Malaysia, and Singapore
The spinning vortex of Saturnâs north polar storm resembles a deep red rose of giant proportions surrounded by green foliage in this false-color image from NASAâs Cassini spacecraft. Measurements have sized the eye at a staggering 1,250 miles (2,000 kilometers) across with cloud speeds as fast as 330 miles per hour (150 meters per second).
On this day in 1846 was discovered the planet Neptune.
The ice giant Neptune was the first planet located through mathematical predictions rather than through regular observations of the sky. (Galileo had recorded it as a fixed star during observations with his small telescope in 1612 and 1613.) When Uranus didnât travel exactly as astronomers expected it to, a French mathematician, Urbain Joseph Le Verrier, proposed the position and mass of another as yet unknown planet that could cause the observed changes to Uranusâ orbit. After being ignored by French astronomers, Le Verrier sent his predictions to Johann Gottfried Galle at the Berlin Observatory, who found Neptune on his first night of searching in 1846. Seventeen days later, its largest moon, Triton, was also discovered.
Neptune is invisible to the naked eye because of its extreme distance from Earth. Interestingly, the highly eccentric orbit of the dwarf planet Pluto brings Pluto inside Neptuneâs orbit for a 20-year period out of every 248 Earth years. Pluto can never crash into Neptune, though, because for every three laps Neptune takes around the Sun, Pluto makes two. This repeating pattern prevents close approaches of the two bodies.
Nearly 4.5 billion kilometers (2.8 billion miles) from the Sun, Neptune orbits the Sun once every 165 years.Â
Uranusâ blue-green color is also the result of atmospheric methane, but Neptune is a more vivid, brighter blue, so there must be an unknown component that causes the more intense color.Â
Despite its great distance and low energy input from the Sun, Neptuneâs winds can be three times stronger than Jupiterâs and nine times stronger than Earthâs.
Winds on Neptune travel faster than the speed of sound.
In 1989, Voyager 2 tracked a large, oval-shaped, dark storm in Neptuneâs southern hemisphere. This âGreat Dark Spotâ was large enough to contain the entire Earth.
Neptune has five known rings. Voyager 2âs observations confirmed that these unusual rings are not uniform but have four thick regions (clumps of dust) called arcs. The rings are thought to be relatively young and short-lived.
Neptune has 14 known moons, six of which were discovered by Voyager 2.
Triton, Neptuneâs largest moon, orbits the planet in the opposite direction compared with the rest of the moons, suggesting that it may have been captured by Neptune in the distant past.Â
To know more about the planet Neptune click here and here.
Images credit: NASA/JPL- Caltech (some images processed by Kevin M. Gill)
Gorgeous! And an example of true cultural exchange between two artists from two cultures collaborating.
Also - did I mention gorgeous??? Holy heck!
âWhile the designs retained the robeâs traditional shape, Â the fabric used in the creations are sourced primarily from Senegal and Nigeria, according to Nigerian site Konbini.â
A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers.
The first known globular cluster, now called M22, was discovered in 1665 by Abraham Ihle, a German amateur astronomer.However, given the small aperture of early telescopes, individual stars within a globular cluster were not resolved until Charles Messier observed M4 in 1764. (To learn more, click here).
Credits: NASA, ESA, STScI and A. Sarajedini (University of Florida)
