Physics of James Webb Space Telescope


There is another good reason to use infrared light on JWST: It is difficult to see distant celestial objects because of the air and dust that is detritus of ancient stars. This can scatter visible light more easily than it does with infrared waves. In fact, infrared sensors can see through the clouds more than telescopes can.

Since JWST is looking in infrared mode, scientists will need everything to be as black as possible around the telescope. This means that the telescope must be freezing to prevent radiation exposure. This is one reason it has a sunscreen. It will block sunlight from large objects to keep them cool. It also helps to turn off the light so that the telescope can be turned off take less light from exoplanets as they orbit their brightest stars. (Otherwise, it will be like trying to see in the dark when someone lights a flashlight on your face.)

How Does JWST View Its Time?

Light and waves that move really fast, very fast. In a matter of seconds, light could travel around the globe more than seven times.

When we look up at the night sky, we should think about the time when light travels from the object to the telescope or to our eyes. For example, light from the nearby star Alpha Centauri takes 4.37 years to reach Earth. So if you look at the sky, you are looking at 4.37 years ago.

(In essence, everything you see is ancient. The moon is visible about 1.3 seconds in the past. If you see it very close to Earth, Mars is three minutes ago.)

The theory is that the JWST can see over 13 billion years ago, up to the point of evolution when the first stars were formed. It’s amazing, if you think about it.

What is Lagrange Point?

The Hubble Space Telescope is inside otsika Earth orbit, which is good because it has become possible for air travelers to use it when needed. But JWST will be a long way off, at the L2 Lagrange site. But what is the location of Lagrange?

Let’s think about Hubble around the Earth. For every moving object, there is a need for center force, or gravity in the center of the circle. If you turn the ball over the rope around your head, the force that pulls in the middle is the twisting of the rope. For Hubble, this central force is a gravitational force because of its connection to the Earth.

As the object moves away from the Earth, this gravitational force decreases. As a result, if the telescope were to move in a higher direction (larger circular motion), the center force could be reduced. To stay in the loop, Hubble had to take a long time to get around. (We can say that it has a low angular velocity.)

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