January’s Talk

“Magnetospheres of the planets”

Catriona Jackman is an Associate Professor at Southampton, and her main interest is in the outer planets and Mercury.

She has worked on Cassini since the beginning of her doctoral studies, and reminded us first of our early misconceptions about the outer reaches of the Solar System.

She started off with a kind of ‘did you know’ session, so I’ll continue in the same frame of mind, and hope someone reads this.

Did you know?

  • Jupiter’s magnetic field was first identified by Bernard Burke and Kenneth Franklin in 1955.
  • Have you heard of Gary Flandro? Well?  In the 1960s he realised that there would be a planetary alignment not to be repeated for 177 years.  He was the one who got JPL to start putting together plans for the two Voyager missions.  In 1966.
  • Of course you’d have to run the gauntlet of the Asteroid Belt first. Well that was fake news in the end.
  • Jupiter comes in very useful for gravity assists, because of its great mass. The lengthy Ulysses mission did a flyby of Jupiter in 1992 in order to get enough momentum to do an orbit over the Sun’s poles.  Ulysses was able to show how the Sun’s magnetic field interacts with the Solar System, and that was far more complex than expected.
  • The three Galilean satellites Io, Europa and Ganymede have an orbital resonance: four orbits of Io equal two of Europa equal one orbit of Ganymede. This is one reason Io gets gravitationally churned up so much.  Jupiter’s magnetic field also affects Ganymede; Ganymede also has a magnetic field.
  • The Cassini-Huyghens mission as revealed that Enceladus is a possible harbour for life. (-even more so than Europa, according to Prof Jackman, because it has molecular hydrogen, and this could support life.)
  • The Juno mission has provided us with some wonderful views, as has New Horizons, but it is still not known whether Saturn has a solid core.

Before you run off and google all this interesting stuff I just would like you to remember a familiar face of RAL, who I was surprised to find that she had only given two talks to us since 2103, but seemed far more public than that.  She was very approachable and loved her science.  She showed us round RAL when I went there for a tour some years ago.  There is a wonderful write up on her in the latest SPA magazine.  She was a stalwart of the SPA, having held posts as President and Treasurer.  Let’s remember her fondly, Dr Helen Walker (1953-2017).

Clear skies

Some daylight astronomy

If you fancy some daylight astronomy then the Moon will be occulting the bright star Aldebaran at 16:37GMT 23rd February 2018. The bright star should be visible in small telescopes just before it disappears behind the dark limb of the Moon. It reappears at 17:44GMT.

The picture shows Aldebaran just before ingress at 16:35GMT:


And then just after it’s reappearance at 17:45GMT:

Clear skies.

The Great Red Stop and a shadow transit

On the Morning of the 13th February 2018, 6am GMT, Jupiter’s Great Red Spot will begin its transit across the Earth facing disk of the planet. At the same time you will be able to see the jet black shadow the moon Europa on the disk as shown  in the picture below:

On the 24th February, also at 6am GMT, Ganymede’s shadow will cross the top of Jupiter’s disk.

Clear skies.

Planetary triangles

On the morning of 9th February 2018 the Moon, Mars and Jupiter form a nice right angled triangle in the morning twilight sky. The picture shows the positions of the planets at 6:30am GMT on the 9th February 2018:

In the opposite direction, Saturn forms another right angle triangle with the Moon and Mars.

Clear skies.

Oxford Stargazing 2018

The society will have a stand at this event tomorrow (27/1), do come and see us. If the weather is clear you’ll be able to look through telescopes at our nearest star and other objects. It takes place at the Denys Wilkinson Building, Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH between 1pm and 9pm. See here for more details.