The first on our tour is one of the best telescopes that any Australian astronomer has access to: the creatively named "Very Large Telescope" (VLT) located at Paranal Observatory in Northern Chile. This telescope is owned by the European Southern Observatory (ESO), of which Australia is an auxiliary member.

The VLT is somewhat of a misnomer, as it is actually four telescopes, each with a primary mirror diameter of 8m. There are also four smaller, "auxiliary" telescopes, each with a diameter of 1.5m.

The ingenious nature of this set of telescopes is that they can all be combined into one telescope with an effective diameter of more than 100m, through a technique known as interferometry. One of our first Sunday Space articles covered interferometry and the VLT.

The Keck telescopes are two of the largest of their kind in the northern hemisphere, located on the summit of Mauna Kea in Hawaii. Each of these telescopes boast a whopping 10m diameter mirror, made up of 36 smaller hexagonal mirror segments that operate as a single mirror.

However, these telescopes hold a secret: all of the light from both telescopes gets sent to the scientific instruments. When you sum up the total light collecting area from both telescopes, they can claim the title as the world's largest optical telescope. The Gran Telescopo Canarias (GTC) from the Canary Islands has a larger area than either single Keck telescope, but not when they're combined.

We've been mainly focused on ground telescopes, but we shouldn't leave out space telescopes. While they may not have the sheer size of the telescopes described above, being above the atmosphere grants them an image quality that arguably surpasses even today's largest telescopes,

The most well-known space telescope, and perhaps the mastermind behind at least half of the most well-known and beautiful images of space, is the Hubble Space Telescope. Despite launching in 1990, it is still producing world class science today with its 2.4m mirror. It flies in Low Earth Orbit, about 500km above the ground, and completes an orbit of the Earth in a bit more than 90 minutes.

The final telescope we'll discuss is the Gaia Space Observatory, a spacecraft owned by the European Space Agency (ESA) and located at the Sun-Earth L2 Lagrange point. This is a point in space where the gravity from the sun and Earth effectively cancel out, allowing it to remain roughly stationary with respect to the Earth and sun.

Gaia has a smaller mirror than Hubble (1.5x0.5m), but has an important goal: provide the most precise positions and distances of all the stars in the Milky Way galaxy. Since launching in 2013, it could be argued no other telescope has revolutionised galactic astrophysics as much as Gaia, and more is still yet to come!