Science with the world’s largest telescope by Dr Katharine Johnston 10/12/25
Did you know that a singular antenna in the ALMA telescope weighs almost as much as a super pod of 70 beluga whales? Each of ALMAs antennas weigh 100 tons each [1] whereas the super pod of whales weighs up to 105 tonnes (one beluga whale weighs up to 1.6 tonnes)! [2][3]
Why the link to whales you may wonder? As we know, whales use frequencies to navigate, and perceive their environment, which is also known as echolocation. Some telescopes use frequencies to do the exact same thing but in space. In this seminar, Dr Johnston discusses several large telescopes and how they work so let’s get into it.
The Telescope
Although we are unsure on who truly invented the telescope, it is known that a Dutch spectacle maker in the 1608s, known as Hans Lipperhey, made public a new lens-based instrument that made far away objects seem much closer. [4] Hans published his design so well that the news reached Galileo in Italy in 1609, and within a year, Galileo improved this design and built his own telescope. Everyone believed that Galileo was the one to invent the telescope due to him discovering Jupiter (quite unfair to Hans).[5]
Ever since then, the use of telescopes continued increasing and the telescope itself kept evolving thus becoming an important scientific instrument and changing our perception of the universe we live in. Right now, there are several types of telescopes dotted all over the world, ranging in shapes and sizes and in today’s seminar, Dr Johnston covers big optical and radio telescopes.
Optical and Radio telescopes
As Dr Johnston covered, big telescopes are for improved resolution and higher sensitivity. This means that for optical telescopes, the more light particles you have, which are called photons, the more signal you have. Whereas for radio telescopes, the longer the wavelength, the bigger the telescope you need to observe with the same detail.
For example, ESO’s very large telescope (VLT) is a facility for European ground-based astronomy, and it is one of the most advanced optical telescopes. It is made up of four-unit telescopes with main mirrors of 8.2 metres in diameter, as well as four movable 1.8 metre auxiliary telescopes. [6] How does it work you may ask? Well, it is a telescope that gathers and focuses visible light, sometimes infrared or ultraviolet, from far away objects creating magnified images for data collection or even photography. However, when observing with an optical telescope, we deal with a lot of dust that is either silicon or carbon based so we needed other ways to take images. This is where the radio telescopes come in.
A radio telescope isn’t your stereotypical “look through the eye piece and observe” kind of telescope. A very good example of this is the ALMA telescope (Atacama Large Millimetre/Submillimetre Array). This is the most powerful radio telescope in the world so let’s talk about it.
The ALMA telescope is an international observatory located in Chile’s Atacama Desert. It is made up of 66 antennas that work as one giant radio telescope. These antennas collect faint radio waves from space, focusing them onto a receiver which converts the waves into electronic signals that computers then process to create images and data. This reveals star or planet formation and even molecules like amino acids. Radio waves have the longest wavelength in the electromagnetic spectrum, ranging from the size of a football to much larger than our planet and we cannot see them. [7] The light humans can see with their eyes is part of a range of radiation known as the electromagnetic spectrum where we can only see a tiny portion of this spectrum known as visible light. [8] Hence why a radio telescope is very important here. It allows astronomers to study invisible phenomena such as pulsars, cold gas clouds and even much colder planets that your usual optical telescope would not be able to observe. Even more helpful, radio telescopes are capable of penetrating dense cloud of gas and dust, allowing us to see what is hidden behind them, something that an optical telescope cannot do.[9]
Why do we need them
Ever since telescopes were invented, thousands of exoplanets have been discovered, some of which are in the “habitable zone”, where water, and maybe even life, might exist. Sadly however, no telescopes to this day have the light collecting power needed or even the correct instruments, to discover these faint signals that could improve our understanding of exoplanet chemistry. [10]
Although telescopes might seemingly not be useful in a lot of situations, they have helped scientists discover and understand more about our universe than they would have without them. As telescopes keep evolving, so does our technology to build them. One of the World’s largest interferometers, known as Event Horizon Telescope (EHT), has a maximum baseline of 10700km, combining many telescope facilities from all around the world, including ALMA. That on its own is incredibly impressive, so imagine what more can be done if this type of technology keeps improving.
Conclusion
From whales using echolocation to telescopes using frequencies to get pretty pictures (and important data), we have reached the end of our discussion.
Telescopes have evolved to become a key instrument in spatial research, all the way from Hans Lipperhey’s lens-based instruments in 1608 to the upcoming Extremely Large Telescope (ELT) expected to be completed in early 2027 in Chile’s Atacama Desert. As we have learnt from Dr Johnston during this seminar, there are many types of telescopes placed all around the world all capable of gathering images and data in their own way, whether that is through optics or capturing and processing radio waves. Telescopes such as ALMA and VLT have helped us gather a much better understanding of the universe we live in, and by understanding how they work, scientists will continue improving telescopes, allowing us to push the limits of what we can see.
References:
[1] Moskowitz, C. (2013) 8 cool facts about the ALMA telescope. Space.com. Available at: https://www.space.com/20130-alma-telescope-cool-facts.html
[2] Georgia Aquarium (no date) Beluga Whale. Available at: https://www.georgiaaquarium.org/animal/beluga-whale/
[3] WWF Arctic (no date) Beluga whale. Available at: https://www.arcticwwf.org/wildlife/beluga-whale/
[4] Royal Museums Greenwich (no date) The history of the telescope. Available at: https://www.rmg.co.uk/stories/space-astronomy/history-telescope
[5] Let’s Talk Science (no date) Optical telescopes. Available at: https://letstalkscience.ca/educational-resources/backgrounders/optical-telescopes
[6] European Southern Observatory (no date) Very Large Telescope. Available at: https://www.eso.org/public/unitedkingdom/teles-instr/paranal-observatory/vlt/
[7] National Aeronautics and Space Administration (no date) Radio Waves. Available at: https://science.nasa.gov/ems/05_radiowaves/
[8] National Aeronautics and Space Administration (no date) Wavelengths Science Behind the Discoveries. Available at: https://science.nasa.gov/mission/hubble/science/science-behind-the-discoveries/wavelengths/
[9] Institut de Radioastronomie Millim�trique (no date) Understanding radio telescopes. Available at: https://iram-institute.org/observatories/understanding-radio-telescopes/
[10] Center for Astrophysics | Harvard & Smithsonian (no date) Why do we need an extremely large telescope like the Giant Magellan Telescope?. Available at: https://www.cfa.harvard.edu/big-questions/why-do-we-need-extremely-large-telescope-giant-magellan-telescope
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Presentation: 13/15
You have followed the criteria of including the speaker’s name, title and date of the seminar, shown clearly at the start of the blogpost.
Content: 14/15
Conveyed the mechanisms behind ALMA array by summarising the majority of the content in the Katharine ‘s seminar.
Context: 13/15
Provided good background on why radio waves are used to see through interstellar dust.
Style: 13/15
It is persuasive to read due to the immediate hook of the rhetorical question and use of concepts that are common knowledge in the opening paragraph. As well as the blogpost explains concepts that are foreign to general public in relatively simple terminology, i.e. Wein’s law
Other sources: 15/15
Referenced additional sources for readers to explore for the factuality of the blogpost content.
Overall Mark: 14/15
Feedback:
Misspelt dynamically ,“dynsmicslly ”, the bullet point list needs a spacing with the following paragraph possibly expand on why the ALMA has such a high altitude.
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- Blog overall presentation (2/3)
The key information is included, a few minor spelling mistakes and the layout seems a little blocky
- Accurate reporting of the seminar’s take-home message (3/3)
A lot of the general and technical is covered to a good standard
- Accurate contextualisation of the research topic (3/3)
The research topic of the seminar is covered very well
- Additional assessment using external sources with a direct quote (3/3)
Good variety of sources for an in-depth further reading
- Writing style and technical level for a lay audience (2/3)
For a lay audience the writing style is good, but again the whole thing seems a little bit blocky. Perhaps smaller sections/paragraphs could help