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In 1623, Italian physicist Galileo Galilei had an idea that changed the history of science: He dedicated an entire summer to observing the sun through a telescope.
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This brilliant idea led him to deduce that the sun was not a perfect sphere, but had spots that moved over time.
Galileo also discovered craters on the lunar surface, named Jupiter’s four major satellites (Europa, Io, Ganymede, and Callisto), and intuited that Saturn had rings.
The use of the telescope (an instrument previously known but never used to observe the sky) opened up new and exciting perspectives.
Ever since Galileo’s observations, telescopes have enabled us to see parts of reality that we cannot otherwise experience.
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Since then, astronomers have been working to design instruments that allow us to go further in our conception of the universe. Bigger telescopes are able to capture more light and therefore reach farther away.
Furthermore, we have long been developing observational tools capable of observing other lengths of the electromagnetic spectrum; that is, light that our eyes cannot capture.
Today we have great allies to observe the full scale of the universe. In this article, I will discuss three of them, which are among the problems that have given scientists the most pleasure in recent years.
The Great Telescope of the Canary Islands
The Gran Telescopio Canarias has a mirror diameter of 10.4 metres: the largest optical telescope on Earth.
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The Grand Canary Telescope (GRANTECAN) is located at the Roque de los Muchachos Observatory on the island of La Palma. The primary mirror is 10.4 meters long, making it the largest optical telescope currently on Earth.
Its dominance is threatened by the construction of the future ELT (Extremely Large Telescope) in Chile, which will have a 39-meter primary mirror. It is expected to debut in 2028.
GRANTECAN’s instruments enable it to operate in the optical and infrared range, a type of radiation that is invisible to our eyes, allowing us to study interstellar dust, among other things. Due to its characteristics, we observe a large number of stars: extrasolar planets, evolved stars, galaxies with very low brightness, etc.
Its discoveries include the detection of a galaxy (UG00180) 500 million light years away, and the discovery of TMTS J0526B, the smallest star ever observed. It is only seven times more massive than Earth.
ALMA, Atacama System
This string of mutually synchronized satellites, located in the Atacama Desert, is the largest “interferometer” on Earth.
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ALMA is the acronym for Atacama Large Millimeter Array, which means the Large Atacama Millimeter-wave “chain” or “system.” Today, it is the largest interferometer on Earth.
An interferometer consists of an array of radio telescopes that observe the universe in the radio frequency range, the least energetic electromagnetic waves in the spectrum.This is done because a single antenna provides images with low resolution: they look very pixelated. If we use multiple antennas to observe the same object at the same time, we will get much higher quality.
ALMA is located in the Chilean Chajnantor Plain, a vast arid plain about 5000 meters above sea level, and has 66 antennas with diameters of 7 and 12 meters. Its different configurations allow us to unravel the “cold” Universe that is invisible to the naked eye.
Thanks to this powerful observatory, we have thus been able to observe protoplanetary disks (from which planetary systems will emerge), galaxies in formation or the death of numerous stars.
Milestone for humanity: First image of black hole at the center of galaxy M87
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However, the greatest achievement of ALMA’s participation was the first-ever “photo” of a black hole. To create it, its data was combined with data from other radio telescopes spread across the Earth, a collaboration called the Event Horizon Telescope.
It is the supermassive black hole inside the M87 galaxy and is the first image of an invisible object. It was released in 2019 and was a milestone for humanity.
James Webb
With millions of dollars invested and a revolutionary set of folding mirrors, James Webb is the most advanced telescope we have ever sent into space.
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However, there are more than just telescopes on the Earth’s surface. The main example is the James Webb Space Telescope, a space telescope built by a collaboration of 14 countries. It is operated by the European (ESA), American (NASA) and Canadian (CSA) space agencies.
Its main goals include observing some of the most distant objects in the Universe, such as the formation of the first galaxies, and studying the formation of stars and planets.
Although its mirror diameter (6.5 meters) is smaller than that of the best ground-based telescopes (such as GRANTECAN), it has one advantage that puts it at the forefront of today’s astronomy: outside the atmosphere, you can get extremely sharp images.
The James Webb Telescope’s modern near-infrared camera has provided stunning details of our solar system’s giant, Jupiter.
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Its first scientific data only date back to 2022, but it already allows us to observe the oldest galaxies known to date (the Messier galaxies), supernova remnants or amazing photos of the planets in our Solar System.
The image quality means we have high expectations for this space giant. We will continue to look further afield.
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