Astronomy is facing the end of the era of monster telescopes because astronomers have already seen most of the bright objects in the sky. Larger telescopes collect more light, which allows them to see fainter objects, more distant galaxies, and older stars. However, astronomers are now looking for dimmer objects.
Astronomers are exploring alternative techniques to enhance observations without the need for a large telescope. One technique is interferometry, which combines observations from multiple telescopes to mimic the resolution of a larger instrument.
Some large telescopes currently under construction include:
- ESO’s Extremely Large Telescope (ELT) Located in Chile’s Atacama Desert, this telescope is expected to see its “first light” by 2028.
- Giant Magellan Telescope Located at Chile’s Las Campanas Observatory, this telescope is due to be completed in about 10 years.
Other large telescopes include:
- James Webb Space Telescope (JWST): This telescope will study forming stars and galaxies and has a primary mirror 6.5 meters in diameter.
The reasons boil down to cost (unsurprisingly), engineering and the implacability of geometric laws. That last factor will be crucial in limiting the size of jumbo telescopes. Astronomers sometimes call telescopes “light buckets” because they collect light falling from the sky like a bucket in the rain collects water
Space telescopes are more expensive to build and maintain than ground-based telescopes. The James Webb Space Telescope is expensive because it’s a unique, handmade device that requires a lot of skilled labor
However, space telescopes have several advantages:
- Clearer view: Space telescopes are above the Earth’s atmosphere, which blurs and distorts starlight.
- Observe all wavelengths: Space telescopes can observe radiation that the atmosphere absorbs or scatters, such as UV, X-ray, gamma ray, and some types of infrared.
- Twenty-four hour observations: Space telescopes can make observations around the clock.
- Cooler infrared images: Space telescopes can cool down to take clean infrared images
Astronomers want larger telescopes because they can:
- See more detail: Larger telescopes have better resolution and can see fine details.
- See fainter objects: Larger telescopes can detect fainter objects, such as planets, stars, and galaxies.
- See farther into space: Larger telescopes can see deeper into the universe.
- See farther back in time: Light takes time to travel, so astronomers can look back in time by studying more distant objects.
Doubling the diameter of a telescope’s lens increases its light-gathering power by a factor of fou
Telescopes are like time machines because they allow us to see distant objects as they were in the past. Light travels at a finite speed of 300,000 kilometers per second. This means that when we look at distant objects, we see them as they were when the light was emitted. The farther away we look, the further back in time we see.
For example, the light from Alpha Centauri that reaches our eyes today left the star four years ago. This means that when we look at Alpha Centauri, we see it as it was four years ago.
The James Webb Space Telescope (JWST) is a powerful time machine that can see back over 13.5 billion years. This allows it to see the first stars and galaxies forming in the early universe
Here’s some information about future telescopes:
- LUVOIR NASA plans to replace the Hubble telescope with the Large UltraViolet Optical InfraRed surveyor (LUVOIR) around 2039.
- Nautilus Space Observatory This proposed telescope would replace large mirrors with a thin lens that is lighter, cheaper, and easier to produce.
- Small modular satellites Instead of a single telescope, a team wants to send several small satellites to the sun.
- Future space telescopes These telescopes could be 100 meters across, constructed in space, and bent into a precise shape.
- E-ELT, Thirty Meter Telescope, and Giant Magellan Telescope These telescopes combine light-gathering power with high-resolution imaging.
- Roman Telescope This telescope will count billions of stars and image exoplanets that are close to their parent star.
NASA is also evaluating four other possible designs for launch in the 2030s:
- Origins Space Telescope
- Lynx X-ray Surveyor
- Habitable Exoplanet Imaging Mission (HabEx)
- Large UV Optical Infrared Surveyor (LUVOIR)
Universe discoveries 