James Webb Telescope distance and Hubble Space Telescope distances from Earth

Space is mostly just that – empty space. There is really only one thing getting in the way of our view of the distant stars and planets: Earth’s atmosphere. When it is daytime here on Earth, the atmosphere scatters light from the Sun and creates a blue coloured sky. Our atmosphere also distorts light from distant stars at night, and this is why stars appear to twinkle. Modern cities also create viewing issues. The light from street lamps and building lights goes up into our sky creating light pollution, and the atmosphere reflects some of that light back down at us. This effect makes the night skies brighter, and it is harder to see fainter celestial objects when in the middle of a big city. Terrestrial telescopes can bring far-off celestial objects into extreme focus, but cannot compare to the epic images produced by extra-terrestrial observatories.

In the 1940’s, Lyman Spitzer published his paper “Astronomical Advantages of an Extra-terrestrial Observatory” and scientists focused on achieving this astronomical feat. The Orbiting Astronomical Observatory (OSO), was launched in the 1960’s with a telescope much different to the one created by Galileo in the 1600’s. Shipping items into Space is a rather expensive endeavour, so the equipment onboard the OSO was to collect light on the ultraviolet side of the spectrum, rather than visible. It wasn’t until Hubble’s launch in 1990 that we received the full colour images of nebulae, stars and galaxies.

In 2015, Hubble celebrated 25 years of operation. Its final service mission was in 2009 but NASA scientists have committed to continue using Hubble for as long as it, and the budget lasts. The launch of Hubble’s successor, the James Webb Space Telescope (JWST) is scheduled for 2018. The JWST will operate about 1,500,000km from Earth – almost four times farther than the Moon and over 2,000 times farther away than Hubble. At this distance the JWST will orbit the Sun in the same time it takes to orbit the Earth. Meaning that once it reaches a stable orbit, it won’t have to continually adjust its direction to face away from the Sun, or readjust its sun shield. Blocking the heat and light from the Sun is crucial for optimal infrared observations because temperatures need to be below -220°C. It will offer unprecedented resolution from long-wavelength visible (reds and oranges) to the mid-infrared with its primary light collecting mirror area being about five times larger than Hubble’s. Because of this, JWST’s instruments will be able to see millions of light-years further than any other telescope. When it looks into the farthest reaches of our universe, it will give a peek into how the first stars and galaxies were created. Not only that, but it will also examine planetary systems and possibly discover how unique the formation of life in our universe is.