Sep 16 – 2B03 16/09/2011 9:20:00 AM
1 weakness of previous definitions -> they apply only to our solar system;
we may want one that applies to our solar systems.
BBC News – Distant world ‘has rocky surface’
Up until this point, other plants we considered only to be gas.
CBC News - Potentially habitable planet found
Rare discovery to have another rocky found – right distance from
star -> may be able to harbour life.
CBC News – Planet with 2 suns discovered
Binary system – planet orbits 2 stars. Gas planet.
Like Star War’s Tatooine
Those 2 discoveries are recent – last week.
Most (over 99%) mass in our solar system is from our Sun.
Midlife star –
o Nuclear burning in its core
In a few billion years, the Sun will be so hot that it will burn away
life on Earth.
200 million years to go around the Milky Way – orbit it.
Sun will grow like fuckin’ CRAZY.
AU – astronomical unit – distance (diameter) between sun and earth
plato – 40 AU
We are at 1 AU. Sun as a red giant will have a diameter of 2 AU,
therefore Earth will be fucked.
Sun will become so large that it will engulf the rocky planets.
Gravity wont change as sun grows. Anything outside sun will have same gravitational force.
Picture of Hubble Deep field – showing similar one (opposite)
We were looking far away from the stars.
This picture, we are looking at the heart of the galaxy, lots of stars.
How do you determine distance to stars? Straighforward – uses geometry.
If we see a star in July, and ten we see it in January, it will
appeared to have moved if it is close. The further away, the closer
it gets to background stars, the smaller the effect is.
Parallax effect – similar to closing one eye and then another
We use relative positioning.
Distances to stars - another unit (besides AU),
Parsec (1) = 3.3 light years.
Really convenient for parallax !
Furthest star - generous – 100 000 light years (in the milky way)
Incredibly small percentage – a very small fraction may have
burned out, but the percentage is very, very small.
I was wrong before (in regards to our milky way)
Interstellar material – orion nebula – bunch of mat