Cambridge Astronomical Association
Cambridge Young Astronomers


Speaker Meeting

The Michael Penston Lecture
Friday 15th March 2019
Start time : 20:00

Speaker :

This lecture is the annual Michael Penston Lecture : Michael was based here at the Institute of Astronomy.

In 1990 he was due to give a talk to the CAA, but had to cancel because of illness. Sadly, Michael died soon afterwards. In March 1991 the CAA held a lecture in memory of Michael, and a collection was made for Cancer Research. By the following year a fund had been set up in his name, administered by the Royal Astronomical Society, to help up-and-coming astronomers establish themselves in their chosen profession. Each year, at the end of the lecture we have asked CAA members to make a donation to this fund.

Tonight we are very pleased to welcome Professor Wyn Evans to give us an update on the progress in analysing the enourmous amounts of new data being gathered by the Gaia satellite.

Gaia is a scanning satellite launched by the European Space Agency in December 2016. It is measuring the positions, distances and motions of stars in our Milky Way Galaxy with unprecedented precision. It has revealed an unruly picture of a beaten-up Galaxy, never at rest. Gaia has uncovered evidence of the most recent major merger of the Milky Way with a dwarf galaxy (the Sausage galaxy) about 8 to 10 billion years ago. This huge smash-up helped create the Milky Way's central bulge, disk and outer halo of stars. The debris of this head-on crash is all around us.

Gaia has shown us many other star streams from smaller mergers that criss-cross the Galaxy, stellar wreckage still intact after billions of years. It has shown us that another intruder -- the nearby southern irregular galaxy, the Large Magellanic Cloud -- is readying to knock our Galaxy around. Though this encounter is still 2 billion years in the future, the Large Magellanic Cloud is already twisting the outer parts of the Milky Way, softening us up before the Great Cataclysm.

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