Why is the Hubble Space telescope able to see farthest in the universe?

Question

What determines how far a telescope can see in the universe? How does recording data for a very long time (~10 years) help? If we could build a telescope which work at microwave region, will it be a better telescope (so that we could see even farther)?

Answer 1

You can think of telescopes as "light buckets" that collect light from the stars and distant galaxies. The light from these objects travel millions of light years to reach the telescopes. The more light these buckets can collect, the more details they can see of those objects and beyond. The more distant photons (light) can reach telescopes, the farther they can see.

Hubble is a telescope that orbits the Earth in space, so its observations aren't hindered by light pollution from cities. On top of that, it's a huge light bucket (its primary mirror is more than 2 meters wide). As it stares at a certain section of sky for long periods of time, it can collect that much more light/data.

Observing those distant stars and galaxies in various wavelengths across the EM spectrum will help you to see the different aspects/characteristics of those objects. For example, observing a galaxy in UV will help you to see if it has a lot of young, hot stars.

The James Webb space telescope (JWST), which will be launching next year, will be able to see farther than Hubble since it will be orbiting much farther away from Earth, is a lot bigger (6.5m) and will observe in the IR region. Being able to observe in the IR region will help a lot in seeing further since a lot of the older galaxies have significantly red-shifted. So technically, if you observe space in infrared, you can see further. I hope that helps!