The European Southern Observatory (ESO) is in the process of making the world’s largest telescope. With a fun sense of humor, they called this telescope the Extremely Large Telescope (the ELT). They had previously made a telescope in 1991 – 1998 and called it VLT, which stands for… you guessed it, the Very Large Telescope. The VLT consists of four eight-meter telescopes that combine light to achieve high resolution. The ESO wanted to make a better one, so they started thinking of making the next large telescope.
In the early 2000s, ESO looked into making a telescope called the Overwhelmingly Large Telescope. It was to be a one hundred meter telescope, costing around 1.5 billion euros. Because the OLT did not have high enough rates of success for investing that much money, the project was eventually resized down to 39.9 meters, costing just under 1.1 billion euro. This design was called the Extremely Large Telescope.
The ELT is a reflecting telescope – meaning it will bounce the light from one mirror to another, making it more compact. The overall design consists of five mirrors. The primary mirror has 798 hexagonal mirrors. The secondary mirror is going to be the largest convex mirror ever produced, accurate up to fifteen millionths of a millimeter. For the fourth mirror, it is only two millimeters thick, using advanced optics and magnets to adjust the surface for accuracy. The faint light from distance objects gets reflected and eventually reaches the focus of the telescope where scientific instruments produce extremely high resolution images. They will use four lasers to create a 3D map of the atmosphere.
The telescope will be able to produce images sixteen times sharper than those from the Hubble Space Telescope. Its spectrograph is designed in a way where the telescope will be able to pinpoint action in space and drop what it is doing in order to document it.
The ELT is the largest constructed telescope ever made. It has a protective dome almost 18 meters high, and it is located in Chile, close to the location of the VLT.
The ELT will be able to directly analyze atmospheres of other planets in great detail. It can image the center of the milky way and document stars orbiting black holes. It will be able to detect earth-like planets which is a major step forward to answering the question of if we are alone in the universe, and if other planets like earth exist. The ELT can also look back in time to study the first stars and galaxies, helping us understand how our own galaxy was formed.
It represents a collaboration between nations and will be called the world’s largest “eye on the sky.”
Sources
Launch Pad Astronomy. “World’s Biggest Optical Telescope – ELT.” YouTube, 8 Aug. 2018, www.youtube.com/watch?v=fvjhldjESGo.
European Southern Observatory (ESO). “ESOcast 84: The New E-ELT Design Unveiled.” YouTube, 3 June 2016, www.youtube.com/watch?v=VZObUQTUnvs.
Image sources
Launch Pad Astronomy. “World’s Biggest Optical Telescope – ELT.” YouTube, 8 Aug. 2018, www.youtube.com/watch?v=fvjhldjESGo.
European Southern Observatory (ESO). “ESOcast 84: The New E-ELT Design Unveiled.” YouTube, 3 June 2016, www.youtube.com/watch?v=VZObUQTUnvs.