Posted in Comets
The Royal Astronomical Society will host a meeting with the title From the Outer to the Inner Solar system: The Origin and Evolution of Comets on 9th February at Burlington House in London, UK. Attendance is free.
Here is a link to a two-minute podcast by Dr Al Grauer from the Spreaker ‘Travelers in the Night‘ channel about how some asteroids can have a comet-like tail, and are also responsible for some meteor showers (the asteroid 3200 Phaethon, which passes very close to the sun, is associated with the Geminid meteor shower; this December 2017 Phaethon will pass ‘just’ six million miles from the Earth).
In order to better understand the links between comets and ‘active asteroids’ we will need more information about their composition from future missions.
Unfortunately, a nearly-full moon will hamper observations of the Perseid meteor shower this year (close to 12th August) and the weather in north-west Europe is also not ideal. If you don’t see any Perseids this year, then you may wish to take a look at the International Meteor Organization’s calendar which lists all expected meteor shows for 2017 with comments as to the likely viewing conditions.
Meteor shows are in general due to dust particles shed by comets as they approached the sun on previous orbits. The Perseids are associated with comet Swift-Tuttle, a 27 km large body which last passed near Earth in 1992 and is not expected again until 2126. We see ‘shooting stars’ because the dust particles are traveling at about 60 km/s relative to the Earth, and this is fast enough that air friction heats the tiny dust particles to white heat in the upper atmosphere, about 90 km above us.
Space.com has posted a video showing early Perseids from this years shower, photographed by a NASA all-sky camera.
Posted in Comets
109 years ago today, there was a large explosion over a remote part of Siberia known as Tunguska, the result of what many think was an asteroid or comet that blew up in the Earth’s atmosphere. The explosion has been estimated to be 185 times more powerful than the atomic bomb dropped on Hiroshima in the second world war; trees were flattened upto 50 km from the blast centre, but no impact crater was found.
The BBC has a nice summary in an article published last year of what happened, in non-technical language.