World’s largest Telescopes - Katharine Johnston 10/12/25
Observing galaxies from far away requires telescopes with extremely high resolution. Resolution is related to the wavelength of light being used to observe and inversely related to the diameter of the telescope. So if you wish to see an object in a high resolution you either need to decrease the wavelength or increase the diameter of the telescope.
One major issue with decreasing the wavelength of light is that small particles of dust can block the light from reaching the telescope meaning that the images can be distorted and not accurate. On the other hand increasing the size of the telescope can lead to exponentially higher cost.
One solution to the increase in size is to use telescope arrays. Telescope arrays use multiple smaller telescopes to act like one larger telescope. One example of this given by the lecture is the ALMA (Atacama Large Millimeter/submillimeter Array). ALMA is an array made from 66 antennas and can operate at wavelengths between 3.6mm and 0.32mm [1]
One of the largest telescope arrays is the event horizon telescope. It uses many telescopes from across the planet and has a maximum distance between telescopes of over 10,000Km. In 2019 results from the event horizon telescope were released showing its visualisation of the super-massive black hole M87. The visualisation showed photons orbiting the black hole creating a red ring around the black hole shown in the visualisation, light cannot escape from the center of a black hole leading to a shadow region in the center of the black hole.
Observations of the M87* black hole allowed for the creation of simulations to model the observations shown by the telescope. The models show us the orbital pattern of the photons around the black hole, this shows us that the M87* A super-massive black hole is rotating clockwise relative to earth.
In conclusion, large telescopes and telescope arrays can be used to observe the universe around us and can give us important information on celestial bodies far away from earth.
[1] “ALMA - Atacama Large Millimeter/submillimeter Array”: https://www.eso.org/public/teles-instr/alma/
90561
Great conciseness and external research. Generally reads well, besides the final sentence in the third paragraph repeating ‘black hole’ a lot, but that’s a nitpick. Could use a quote also, but otherwise very good!