How To Derive The Roche Limit

The Roche Limit is the distance that a moon or satellite can be to a planet before the gravitational tides pull it apart. At the Roche limit the gravitational tides from the planet are balanced by the self gravity of the satellite. At closer distances the satellite is pulled apart. When further away from the Roche limit the satellite can hold itself together under its own gravitational forces.

In this video we balance these two forces and find an expression for the distance at which objects would be pulled apart by the planets tides.

How To Use Supernovas For Distance Measurements

Dr Phil Sutton

When discussing the brightness of stars we typically refer to apparent and absolute magnitude. Apparent magnitude of a star how bright we observe a star from Earth compared to the star Vega. Stars bright than Vega have a lower magnitude, while stars dimmer have higher magnitude than Vega. Stars that are further away will have a lower apparent magnitude. Therefore, we can use this relationship to calculate how far away a star is, if we know its absolute magnitude. The absolute magnitude is how bright a star would be from some standard distance, which is 10 parsecs. Knowing the spectral type of the star can help identify its absolute magnitude.

Type 1a supernovas occur when white dwarf stars pull material of a nearby red giant star. Once the white dwarf hits the upper mass limit of 1.4 solar masses it approaches the ignition temperature for carbon. This causes a runway…

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How To Calculate Jupiter’s Mass With A Telescope And The Galilean Moons

Have a telescope that you don’t know what to do with? If you are able to observe Jupiter you can also observe the largest four moons, known as the Galilean moons. By making a note of the relative position of each moon (Io, Europa, Ganymede and Callisto) you can very easily calculate the mass of Jupiter using Kepler’s 3rd law. The moons closest to Jupiter will have shorter orbital periods than those further away.

This short video shows you that by creating a plot of the moons movement over a number of weeks you can get enough information to measure the mass of the Solar System’s largest planet.

Fantastic Worlds and Where to Find Them by Phil Sutton: Lincoln Maths & Physics Week 2021

As part of British Science Week the School of Mathematics and Physics ran a series of public lectures relating to the research done within the school. Phil Sutton gave a talk that introduces how we discover planets orbiting other stars, known as exoplanets. It then finished by taking a brief look at some of the more unusual planets and systems found to date.

The recorded lecture can be found below.

Don Kurtz – Visiting Professor of Astrophysics

Maths & Physics News

Don Kurtz has been appointed a Visiting Professor of Astrophysics in our school till August 2023.

Donwas born in San Diego, California, to an American father and Canadian mother. He obtained a BA in astronomy from San Diego State University in 1970, and his PhD from the University of Texas at Austin in 1976. He was awarded a postdoctoral fellowship for one year at the University of Cape Town (UCT) starting in February 1977. That one year stretched to 24 years, by which time he was a Professor of Astronomy and Life Fellow of UCT. After a short spell at the Observatoire Midi-Pyrénées in Toulouse, France, in 2000, Don moved to the UK, where he was Professor of Astrophysics at the University of Central Lancashire (UCLan), UK, from 2001 until 2020; he is now Emeritus Professor at UCLan. Don was appointed Extraordinary Professor at North-West University (NWU) from 2020…

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Dr Phil Sutton Gives Seminar at Jeremiah Horrocks Institute

On 21st October Dr Phil Sutton gave a seminar at the Jeremiah Horrocks Institute at Uclan about his work with planetary rings, exoplanets and exomoons.

Image credit: NASA / JPL


The Importance of Planetary Rings as Astrophysical Laboratories


The Solar System hosts one of the best natural laboratories for the study of astrophysical processes. Saturn’s rings are close enough that we have been able to study them in great detail with the use of the in-situ spacecraft, Cassini, for over a decade. In this talk, with the use of Saturn’s rings, we will cover the key physics of planetary rings, their interactions with nearby moons and how they can be used to strengthen our planet formation theories. The talk will finish by applying what we have learnt from Saturn’s rings to some recently discovered rings orbiting exoplanets (exorings), and how we can discover unseen exomoons by the signatures they leave within the rings.

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