As of this writing, final preparations are underway for the launch of the James Webb Space Telescope (JWST), scheduled to launch on Christmas Eve.
This telescope is an international project; participants include the United States Space Agency (NASA), the European Space Agency (ESA) and the Canadian Space Agency (CSA). It has been described as the successor to the highly successful Hubble Space Telescope (HST). This project certainly builds on what has been learned with the HST, but the scientific goals of the new telescope are significantly different.
Given the expense and planning involved in successfully building and deploying a telescope in space, why are we doing it?
If you’ve ever done astronomy in your backyard, you’ll know much of the answer.
The turbulent movements in the atmosphere make the images dance and blur, with just naked moments where details appear and then disappear again. It assumes that you can see the stars; cloudy days make optical telescopes unnecessary. Plus, regardless of the weather, you can’t do a lot of sightings during daylight hours. Putting telescopes above the atmosphere eliminates all of these atmospheric problems. Additionally, as long as the celestial objects of interest are not hidden by the Earth or the Moon and are not too close to the Sun, 24-hour observation is possible.
There is another reason to put telescopes in space. Emissions from other objects in the universe range from long wavelength radio waves to very short wavelength gamma rays. The atmosphere is transparent to visible light and is part of the spectrum of radio wavelengths. For the rest of the electromagnetic spectrum, it is partially or even completely opaque. There is significant information in these broadcasts that do not reach the ground, so we have to observe them from space.
The JWST is able to observe at infrared wavelengths, which are blocked by the atmosphere. It will be a useful tool for a wide range of projects. Here are a few.
Investigating the end of the dark ages of the universe. The universe started out as something very hot and very dense. Eventually, it cooled to the point where atoms were able to form. At this point it turned dark, as nothing was hot enough to produce light. Then, about 13.5 billion years ago, the first stars formed, lighting up the universe and ending the Dark Ages. It was then that the universe began to resemble the one we live in today.
What were the very first galaxies like? The first galaxies formed around the time the first stars began to come together. When did galaxies become like the ones we see now?
When the first stars formed, the elements necessary for the formation of planets and life forms did not exist. These are made as waste when producing energy in stars. After a few generations of stars had passed, there was enough of this waste to make planets. This formation occurs inside collapsing clouds of gas and dust. The JWST should be able to penetrate these clouds so that we can see at what point in the history of the universe the planets, and possibly life, may have started.
This new telescope will be a powerful tool for observing the atmosphere of planets orbiting other stars. There are certain elements that indicate the presence of life, such as oxygen in the atmosphere of our world. Knowing – rather than just believing – that we are not alone will be one of the greatest discoveries in our history.
Mars is low in the twilight of dawn. After sunset, Venus is near the southwest horizon, with Saturn to its left, then Jupiter. The Moon will be new on January 2, 2022.
May JWST be just one of the good things happening in 2022. Happy New Year.
Ken Tapping is an astronomer at the National Research Council’s Dominion Radio Astrophysical Observatory.