Distant Worlds

A talk by Matt Lodge

Gas giants, water worlds, lava worlds, and worlds like ours—where are these worlds, and what are they? These are exoplanets, planets that revolve around distant stars light-years beyond our solar system.

Matt Lodge, an astrophysicist from Bristol University, sent our brains into overdrive in his fascinating talk at the library on 10 April. He discussed current research into exoplanets.

How do we know exoplanets exist? One way astronomers have found them is that when they observe a distant star, they see a planet passing in front of that star. They can also measure the wavelengths of the Doppler effect caused by the planet or radial velocity—the mass of a planet causes the star to wobble.

And how do we know what the planets are made of? Certain elements can absorb specific colours, so by using spectroscopy – passing light through a prism – astrophysicists can detect what elements exist on a planet. For example, they can tell that it’s a gas world or a water world.

Matt specialises in the study of minute particles. These reflect light, changing the balance of energy, and thus provide information about exoplanets. Recent observation has shown that our sun is more intense (and the Earth warmer) than was previously thought. This is because particles are not spherical but are all differently shaped.

So far, 5,599 exoplanets have been discovered (the ones nearest us orbit the star Proxima Centauri, about four light-years away). The universe is unimaginably huge, so there must be more out there! Amateur astronomers can contribute to the search via the website arXiv.org; or look at exoplanets.nasa.gov.

Matt also recommends https://stars.chromeexperiments.com (the closest 100,000 stars to us, fully explorable) and https://sky.esa.int/ (high-resolution images that allow you to zoom in on any region of the night sky and see the galaxies that you usually only get to see with more powerful telescopes).