THE HUBBLE SPACE TELESCOPE :

A WINDOW TO THE UNIVERSE

Hello and welcome to Science Fridays with Sabeel. In this show we deal with science and technology. I am your host Sabeel.

In today’s episode we will talk about the recently launched James Webb Space Telescope. We will discuss what this one has to offer, it’s challenges and how it differs from the Hubble Telescope. Stay tuned guys!

The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. The launch of the Hubble Space Telescope, named after famous astronomer Edwin Hubble, was itself a huge leap forward for astronomy. Hubble has meant so much during its 30-year run. For one thing, it’s sent us unforgettable, jaw-droppingly beautiful images. It’s also taught us about the age of the universe, about what happens when stars explode, about black holes. It helped establish many of the boundaries that the Webb hopes to push. Most powerfully, its observations have led scientists to believe the universe is expanding at an accelerating rate, propelled by something so mysterious that scientists simply call it “dark energy.”

The James Webb Space Telescope is a space telescope developed by NASA with contributions from the European Space Agency and the Canadian Space Agency. The telescope is named after James E. Webb, who was the administrator of NASA from 1961 to 1968 and played an integral role in the Apollo program. It is intended to succeed the Hubble Space Telescope as NASA's flagship mission in astrophysics. The telescope was launched into space on the 24th December 2021 – a nice Christmas Eve surprise for any fans of space!

Now let’s talk about what this guy has to offer above it’s big brother. The Webb improves on Hubble in two key ways. The first is just its size: Hubble was about the size of a school bus, whereas Webb is more like the size of a tennis court. This thing is enormous. Webb is by far the biggest telescope NASA’s ever attempted to send into space.

But it’s not just the total size of the contraption that matters. When it comes to reflecting telescopes, the key component is the size of its curved mirror. You could sort of think of a telescope mirror like a light bucket, The more light you can collect in this bucket, the fainter and farther-away things you can see in the universe. Hubble’s mirror was an impressive 7.8 feet in diameter. Webb’s beautiful, gold-hued mirrors combine for a diameter of 21.3 feet. Overall, that amounts to more than six times the light-collecting area.

Welcome back, guys. We were saying that this one collects more light. The Webb’s other advantage is the type of light it collects. Light comes in a lot of different varieties. The human eye can see only a narrow band known as visible light, but the universe contains lots of light outside this range, including the higher-frequency, higher-energy forms: ultraviolet, X-rays, gamma rays. Then there’s the lower-energy light with longer wavelengths: infrared, microwaves, radio. The Hubble Space Telescope collects visible light, ultraviolet, and a little bit of infrared. The Webb is primarily an infrared telescope, so it sees light with a longer wavelength than our eyes can see.

Infrared light is often very old light, due to a phenomenon called redshifting. When a light source is moving away from a viewer, it gets stretched out, morphing into longer and longer wavelengths. Because space is constantly expanding, the farthest things away from us in the universe are moving away from us. And as light travels through space from those distant galaxies, the light is literally stretched by the expansion of space. This is also why the Webb is being launched so far away. Because Webb is an infrared telescope, it needs to be kept cold. The Earth itself is warm and glows in infrared. Anything warm glows in infrared light. If the telescope was warm, it would just glow and see itself. So NASA and its partners are sending the telescope to orbit a point in space called a Lagrange point, a spot where the telescope can orbit the sun, all the while staying cold and in line with the Earth.