Last Thursday our school had a fantastic fireworks evening, the impressive show bringing in spectators from all around Lansdown. Hopefully everybody who attended had a great time, however, the show had only just begun.
After the fireworks ended an Astronomy lecture took place in the Hudson centre, featuring Dr Vicky Scowcroft, who some may recognise from last year’s Pint of Science Festival. She is a Prize Fellow at the University of Bath with a Masters degree in Physics from the University of Leeds and a PhD from Liverpool John Moores University. Having worked as a Postdoctoral Research Associate and then a Senior Research Associate at The Observatories of the Carnegie Institution for Science in Pasadena, California for nine years, she is now part of the Astrophysics group at the University of Bath. She studies variable stars, using them to study the expansion rate of the universe, which she spoke to us about.
Dr Scowcroft began the lecture by explaining how galaxies are laid out, using the piece Perceptual Shift by Michael Murphy as a metaphor for how difficult it is to tell the distance between stars from 2D images. She explained how parallax and the luminosity of stars can be used to measure distances.
During the lecture, Dr Scowcroft told the story of Henrietta Swan Leavitt, an American female astronomer who worked in the late 19th century and early 20th century, studying stars in the Magellanic Clouds (which Dr Scowcroft works on as well!). Leavitt had discovered the relation between the luminosity of stars and Cepheid variable stars – stars which pulsate radially. This relationship, known as the Leavitt law, allowed astronomers to know the true luminosity of a Cepheid by observing its pulsation period. This can then be used to determine the distance to the star by comparing its known luminosity to its observed brightness. Unfortunately, Leavitt did not receive credit for her discovery during her lifetime despite it being incredibly important; it allowed scientists to measure the distance to galaxies too far away and too remote to apply parallax to.
Dr Scowcroft explained how the Leavitt law aided Edwin Hubble to conclude that the galaxy M31, otherwise known as Andromeda, is an external galaxy and not just a cloud of gas within our own. This discovery showed the world that the universe is much, much bigger than we initially thought. Hubble continued his research, also using spectral shifts first measured by fellow astronomer Vesto Slipher at Lowell Observatory, to realise that the universe is expanding! To help us understand, Dr Scowcroft made the amusing comparison of the universe and a cake, saying how every object within it is like a raisin or chocolate chip moving away from the others, but not becoming larger itself. She continued to tell us how scientists later determined that the universe is also accelerating. The more time that passes, the faster it will expand until it eventually rips itself apart! However, this would only happen very far in the future. The rate at which the universe expands is known as the Hubble constant.
After this, we learned a bit more about the future of astronomy and science. Dr Scowcroft told us of the new James Webb Space Telescope which is due to be launched in January 2019. It is much larger than the Hubble Space Telescope, composed of 18 hexagonal mirror segments coated in gold, and will mainly detect near-infrared radiation along with orange and red visible light.
She also told us how the calculation of the Hubble constant by modern astronomers was not getting the same value, which it used to until recently. The LIGO Scientific Collaboration experimented with measuring the Hubble constant using gravitational waves, raising the possibility of it having a range of values. If this ends up being true, physicists may have to revisit the Standard Model and consider a fourth neutrino. Resolving these inconsistent results is a foremost problem and priority in modern science.
Overall, the lecture was very entertaining and broadened our minds, all the while being easy to understand thanks to Dr Scowcroft’s fun but expert way of delivery. As well as teaching us more about the universe and astronomy, the lecture also undeniably reminded us of the limitless world of science and however changing it is.