Telescopes are always a cool subject of exploration, looking out and seeing the plants and stars. But because of these light-emitting stars we can see the planets, and obviously stars. But how do you see something, or even photograph something that doesn’t emit light, rather engulfs it. Well, this is what Katharine Johnston goes over in her seminar ‘science with the world’s largest telescope’.
Astronomers use a clever trick called interferometry, which combines many smaller telescopes into one giant virtual telescope, giving us an earth-sized telescope capable of doing the impossible that’s been set out to achieve. As Katharine explained: “The resolution of a telescope depends on the wavelength and the diameter of the telescope, bigger telescopes give finer detail”.
But building a mirror the size of Earth is impossible. So instead, astronomers place telescopes across the globe and connect them electronically. This is how ALMA in Chile and the Event Horizon Telescope (EHT) work.
ALMA studies cold gas and dust where stars form: “At sub-millimetre wavelengths the dust itself starts to emit, allowing us to measure the mass and structure of star-forming clouds”. Using ALMA, a giant disk of material around a star 25 times heavier than our Sun was imaged, evidence that massive stars may form through rotating disks just like small ones [1].
The EHT goes even further. It links telescopes worldwide to achieve the sharpest vision ever: “The Event Horizon Telescope has the resolution of a telescope the size of the Earth”. In 2019, the EHT released the first image of a black hole, the one at the centre of galaxy M87 [2]. What we see is not the black hole itself, but a glowing ring of light around it: “The bright ring we see is produced by photons orbiting the black hole before escaping toward us”. This ring was predicted decades earlier by physicists modelling how light bends around black holes [3].
Later, astronomers even measured the magnetic fields near the black hole by studying polarized light: “The polarization of the light reveals the magnetic fields that control the flow of matter into the black hole”. Even more remarkably, the black hole at the centre of our own galaxy looks almost the same, proving that black holes follow the same laws everywhere.
So, it’s not just the stuff that’s shining out in the night sky that we can snap photos of, arguably with a bit more difficulty, we can also see, image and study the further darker parts of our universe
References:
[2] EHT Collaboration, 2019 https://r.search.yahoo.com/_ylt=AwrkPHL.kmVp2GMH1gN3Bwx.;_ylu=Y29sbwMEcG9zAzIEdnRpZANEMjk3MzYtR1NLSU4tVUstQ18xBHNlYwNzcg—/RV=2/RE=1768293247/RO=10/RU=https%3a%2f%2fwww.eso.org%2fpublic%2fnews%2feso1907%2f/RK=2/RS=eEtYD0LflIM0oNMgWgiSUiWX.vc-
81177
The presentation is great with the correct date and the name of the speaker is correct. The contents of the report cover the topic of the seminar accurately however it is missing the equations from the seminar which could be added. The context of why the topic is important is present and well done. Plenty of evidence of extra reading on the topic however not in the form of direct quotes. The writing style is appropriate for a lay person.
42890
Overall the blog looks good, you have lots of references and reads very well. As mentioned earlier there are no direct quotes but other than that it is excellent!…
67384
Presentation 3/3: The date, title and name of the speaker are present, and the blog is written in good English and grammar.
Content 3/3: The content covers a great amount of information from the seminar, such as the optical and radio telescopes, interstellar dust, ALMA, VLT, ELT, EHT and more.
Context 3/3: There is a lot of evidence of societal and research contexts which have been well explored and explained. For example, the history of the telescope and the “why we need them” section.
Style 2/3: The writing style is suitable for a lay audience and engaging to read. I liked the use of analogies to explain throughout. The only thing is that the word count may be too high.
External source 2/3: There is an extensive amount of external sources and references evident, but could add a direct supporting/balancing quote as mentioned on the mark scheme.
Final grade: 13/15
Feedback: The work aligns with the mark scheme well. To improve, reduce the word count and add a direct supporting/balancing quote from an external source.
60795
This is excellent. The work is formatted well with subheading making things even clearer for the reader. Also, there are plenty of references which shows that a lot of independent work has been put in.