Webb vs Hubble
Replacement of an old telescope or a successor?
Webb is often called a replacement for Hubble, but in
Hubble's achievements pushed scientists to the ideause longer wavelengths to "go beyond" observations. More distant objects have a high red shift. Thus, an infrared telescope is required to observe these distant objects (for example, the first galaxies to form in the universe).
This is another reason Webb is notreplacement for Hubble; its capabilities are not identical. Webb will primarily look at the Universe in infrared, while Hubble studies it primarily at optical and ultraviolet wavelengths (although it has some infrared capabilities).
Infrared observations allow you to peer behind the curtain of dust and see what lies behind it.
Why does Webb see more?
Light propagates in a frequency range alongelectromagnetic spectrum. Our eyes have evolved to detect a band of the spectrum known as “visible light,” which is not surprising given that our atmosphere blocks many other wavelengths. However, there are many other forms of light that we cannot see both inside and outside our atmosphere.
NASA
Infrared light has a long wavelength andcan pass through objects in space that are blocked by visible light, such as gas and dust. This is why images taken with telescopes that detect infrared frequencies can highlight objects outside those clouds and appear sharper than those taken with other telescopes.
Webb also has a much larger mirror than Hubble. This large light-gathering area means Webb can look further back in time than Hubble is able to do.
In addition, Hubble is in very close orbit around the Earth, and Webb will be 1.5 million km away at the second Lagrange point (L2).
Will Webb take pictures as beautiful as Hubble?
Yes. Besides the fact that with the Webb telescope, scientists will be able to see what they have never seen before, researchers will have the opportunity to observe already discovered objects in a new light. Literally.
The beauty and quality of the astronomical imagedepends on two things: sharpness and the number of pixels in the camera. In both cases, Webb is very similar and in many ways better than Hubble. Although Webb's images will be infrared, they can be converted by a computer into a visible image. In addition, he can see orange and red visible light. Webb's images will be different, but just as beautiful as Hubble's.
Compare telescope sizes
Webb will have a primary mirror with a diameter of 6.5 m,this gives it a significantly larger collecting area than the mirrors available in the current generation of space telescope. The Hubble mirror is much smaller - 2.4 m in diameter and its information collection area is 4.5 m². For James Webb this area is 6.25 times larger. Additionally, Webb will have a significantly larger field of view than Hubble's NICMOS camera. Webb will be able to cover 15 times more space.
How far can Webb see? And what does Hubble not see?
Because of the time it takes for light to travel, the farther we are from the object, the further back in time we look.
This illustration compares different telescopes andhow far they can see. In fact, Hubble can see the equivalent of "baby galaxies", while the Webb telescope can see "baby galaxies". One of the reasons Webb will be able to see the first galaxies is because it is an infrared telescope.
The further the object is, the more we look back.because of the time it takes for light to travel. When we look at objects through an advanced telescope, we see these objects much the same as they were when light first left them 13.6 billion years ago.
Thanks to his ability to see the Universe inWith longer wavelength infrared light, James Webb will be able to see some of the most distant galaxies in our Universe, beyond Hubble's visible/ultraviolet light. This is because light from distant objects is stretched by the expansion of our Universe, an effect known as redshift. Thus, while Hubble was able to view “baby” galaxies, James Webb will begin to peer into their birth.
The universe (and therefore the galaxies in it)expanding. When we talk about the most distant objects, Einstein actually comes into play. The expansion of the universe means that the space between objects actually stretches, forcing the objects (galaxies) to move away from each other. In addition, any light in this space will also stretch, shifting the wavelength of that light towards longer wavelengths. This can make distant objects very dim (or invisible) at visible wavelengths of light, because this light reaches us already as infrared light. Infrared telescopes like Webb are ideal for observing these early galaxies.
Comparing the orbit of Webb and Hubble
The land is located at 150 million. km from the Sun, and the Moon revolves around the Earth at a distance of approximately 384,500 km. The Hubble Space Telescope orbits the Earth at ~ 570 km above it. In fact, Webb will not revolve around the Earth - he will be at a distance of 1.5 million km.
Webb will orbit the Sun at a distance of 1.5 million kilometers (1 million miles) from Earth at the so-called second Lagrange point or L2. (Note that this graphic is not to scale)
Since Hubble is in low-Earth orbit,the space shuttle was able to launch it into space. Webb will be launched on an Ariane 5 rocket, and since it will not be in low-Earth orbit, it is not intended to be serviced by a space shuttle.
Webb's solar shield will block light from the Sun, Earth, and Moon. This will help Webb stay calm and not be "distracted" by near light, which is very important for an infrared telescope.
When the Earth revolves around the Sun, Webb will revolve around it - but will remain stationary in the same place relative to the Earth and the Sun
Webb features
Mirrors
The main Webb mirror has 18 segments,who work together as one; they can all be customized. Its segments have a mass of ~ 20 kg each and a height of about a meter. The coating of the mirrors is so thin that a human hair is 1,000 times thicker! Each segment has its own characteristics.
Why a hexagonal shape?
The hexagonal shape allows for a roughly roundsegmented mirror with "high duty cycle and sixfold symmetry". A high fill factor means the segments are connected without gaps. If the segments were round, there would be gaps between them. The good thing about symmetry is that 18 segments only need 3 different optical recipes, 6 for each (see the right diagram above). Finally, an approximately circular overall shape of the mirror is desirable as it focuses the light into the most compact area on the detectors. For example, an oval mirror produces images stretched in one direction. The square mirror sent out a lot of light from the central area.
This is how the light will enter the Webb telescope.
Sensitivity, resolution and wavelength of the Webb telescope
Webb is so sensitive that he can detect the heat signature of a bumblebee at the distance of the moon and can see features the size of a US penny at a distance of about 40 km.
Webb will see the universe in a light invisible tohuman eye. Although it appears to be primarily infrared light, it can also see red and gold visible light. (Webb's wavelength range is 0.6 to 28.5 microns).
Deploying Webb. How does this happen?
The Webb Telescope team also decided to builda mirror in segments on a structure that folds down to fit into the rocket. The mirror will open after launch: each of the 18 hexagonal-shaped mirror segments has a diameter of 1.32 m.Webb's secondary mirror has a diameter of 0.74 m.
https://www.youtube.com/watch?v=bTxLAGchWnA&feature=youtu.be
What will the Webb Telescope study?
The first stars and galaxies
With unprecedented sensitivity to infrared light, it will look back in time more than 13.5 billion years to see the first galaxies born after the Big Bang.
How galaxies gather
Webb will help astronomers compare the faintest and earliest galaxies with modern great spirals and ellipticals, helping us understand how galaxies assemble over billions of years.
Birth of stars and planetary systems
Webb will be able to see through massive clouds of dust, opaque to visible light observatories such as Hubble, where stars and planetary systems are born.
Exoplanets
Webb will tell us more about atmospheresextrasolar planets, and perhaps even find the building blocks of life elsewhere in the universe. In addition to other planetary systems, Webb will also be studying objects in our own solar system.
Webb's first assignment: he will study Jupiter, its rings and two intriguing moons
Diverse team of over 40The researchers, led by astronomer Inke de Pater of the University of California, Berkeley and Thierry Fouche of the Paris Observatory, have developed an ambitious observing program that will conduct some of Webb's first scientific observations in the solar system. They will study Jupiter, its ring system and its two moons: Ganymede and Io.
It will be a really difficult experimentscientists emphasize. Jupiter is so bright and Webb's instruments are so sensitive that observing the bright planet, its weaker rings and moons, will be a great test of Webb's innovative technology.
Jupiter and his storms
In addition to calibrating Webb instruments forthe brightness of Jupiter, astronomers must also account for the rotation of the planet, because Jupiter completes one day in just 10 hours. Multiple images must be stitched together in a mosaic to completely capture a specific area - for example, the famous storm known as the Great Red Spot - a task that gets more complicated when the object itself is moving. While many telescopes have studied Jupiter and its storms, Webb's large mirror and powerful instruments will provide new insights.
Storm cyclones surround Jupiter's N Pole, captured in infrared by NASA's Juno spacecraft.
Credits: NASA / JPL-Caltech / SwRI / ASI / INAF / JIRAM
Webb will also explore the atmosphere of the polar region,where NASA's Juno spacecraft discovered clusters of cyclones. Webb's spectroscopic data will provide much more detail than was possible with previous observations, measurements of wind, cloud particles, gas composition, and temperature.
Jupiter's rings
All four gas giants of the solar planetssystems have rings, with Saturn being the most prominent. Jupiter's ring system consists of three parts: a flat main ring; a halo inside the main ring in the form of a double convex lens; and a thin ring external to the main ring. Jupiter's ring system is extremely weak because the particles that make up the rings are so small and rare that they don't reflect much light. Near the planet's brightness, they almost disappear, challenging astronomers.
NASA's Galileo spacecraft captured an image of Jupiter's ring system, including a diffuse outer thin ring.
Credits: NASA / JPL / Cornell University
Jupiter's Moon - Ganymede
Several features of Ice Ganymede makeits exciting for astronomers. In addition to being the largest moon in the solar system and even larger than the planet Mercury, it is the only known moon to have its own magnetic field. The team is exploring the outermost parts of Ganymede's atmosphere, its exosphere, to better understand the Moon's interactions with particles in Jupiter's magnetic field.
There is also evidence that Ganymedethere may be a liquid salty sea ocean beneath its thick surface ice, which Webb will explore with detailed spectroscopic studies of surface salts and other compounds. The group's experience studying the surface of Ganymede may be useful in further studying other satellites of the icy solar system, presumably with subsurface oceans, including Saturn's moon Enceladus and Jupiter's moon Europa.
Moon of Jupiter - Io
Unlike Ganymede, another satellite, the teamwill explore Io, the most volcanically active world in the solar system. The dynamic surface is covered in hundreds of huge volcanoes that will eclipse those on Earth, as well as lakes of molten lava and smooth floodplains of solidified lava. Astronomers plan to use Webb to learn more about the effects of Io's volcanoes on its atmosphere.
Another mystery that Webb will consider on Io,Is the existence of "hidden volcanoes" that emit gas jets without the reflective dust that can be detected by spacecraft such as NASA's Voyager and Galileo missions, and therefore still go unnoticed. Webb's high spatial resolution will highlight individual volcanoes that previously would have looked like one large hotspot, allowing astronomers to gather detailed data on Io's geology.
NASA's Galileo spacecraft catches Io in the midst of a volcanic eruption.
Credits: NASA / JPL / DLR
Webb will also provide unprecedented data ontemperature of Io's hotspots and determine whether they are closer to volcanism on Earth today or have a much higher temperature, similar to the environment on Earth in the early years after its formation. Previous observations of the Galileo mission and ground-based observatories hinted at these high temperatures; Webb will continue to research and provide new evidence that may resolve the issue.
Read also
Astronomers have found the best place on Earth for a telescope
Spain and Great Britain record record high temperatures
Germany bans disposable plastic straws, appliances and utensils