As of July 2019, the world’s largest telescope has a staggering mirror diameter of 37.4 feet (10.4 meters), with its closest rival being a set of four telescopes that are 27 feet (8.2 meters). These telescopes are enormous by any metric, and allow people to see the universe at resolutions that are hard to imagine. However, astronomers are far from content at the moment, and are currently building the Extremely Large Telescope (ELT), which will sport an opening of a staggering 128 feet (39 meters).
The ELT is the upcoming flagship telescope of the European Southern Observatory (ESO) that will be built in Chile. It’s expected to enable research that would now be much too difficult with the current telescopes. The ELT’s surface area will be roughly five times as large as the Very Large Telescope, and it can therefore capture the same amount of light in 1/22 of the time. Basically, if the current telescopes would need to integrate for two hours to get a good picture of a galaxy, the ELT could achieve the same in just over five minutes.
This next-generation telescope is still being built, and is estimated to be finished in 2025. In the meantime, the ESO has released a Lego model of the telescope for those who want to see how big it is. The model is built on a 1:150 scale. It consists of 5,274 pieces and is built in a way that allows for the same movement that the real telescope will have.