Transcript Earth - Capital High School

Earth, Stars, and the Universe
Earth
• tends to be hotter at the equator because the
sun’s energy is perpendicular to the earth and
therefore more concentrated
• earth’s seasons are caused by the tilt
(23.5º) of the earth on its axis
• the pole tilted towards the sun is hotter and
the days longer
– more direct
sunlight and
higher
temperatures
Stars
• life cycle varies depending on the size
• all begin life inside a huge cloud of gas (mostly
hydrogen) and dust called a nebula
• then turns into a protostar
– H is converted to He
– gravity squeezes the atoms of a star so
tight that the electrons are stripped away
and the bare nuclei of atoms almost touch
each other
• once nuclear fusion begins, a star is in the
main sequence stage of its life cycle
• for average, Sun-sized stars
– eventually runs out of H
– gets hotter making C and O atoms
– expands outwards making a red giant
– hydrogen fusion stops
• no more energy exploding outward
• gravity pulls matter inwards
• VERY high density, bright, and is called a white dwarf
• for larger stars
– larger elements (up to iron) of the periodic table
are fused together
– eventually may turn into a supernova
• quickly collapses because run out of energy
and gravity is now the strongest force
– core collapses and then rebounds outward with a
shock wave that makes a bright explosion
(supernova)
– at this point, heavier elements are created
• if the leftover core is very, very dense, it may
form a very small neutron star or a black hole
with VERY powerful gravity
Universe (The Big Bang)
The Hubble Ultra Deep Field, or HUDF, is an image of a small region of space in the constellation Fornax, composited from Hubble Space
Telescope data accumulated over a period from September 3, 2003 through January 16, 2004. It is the deepest image of the universe ever
taken in visible light, looking back in time more than 13 billion years. The HUDF contains an estimated 10,000 galaxies. The total field of view
represents only 1 ten millionth of the total sky. THIS MAY NOT BE TRUE, I JUST FOUND IT ON THE INTERNET
• consists of all matter, empty space, and
energy that exists
• objects are so far away, we are seeing what
they looked like millions of years ago
– it takes one year for light to travel 5+ trillion miles
(a light year)
• around 10-20 billion years old
• Evidence
1. is expanding, therefore must have been
smaller at one point
• evident by galaxies’ red shift
– most look red because they are moving away from us
• if they were moving towards us, they would look
bluer (blue shift)
2. cosmic background radiation
– scientists found “noise” in our galaxy that was
the cosmic microwave background radiation
predicted by the Big Bang theory
3. most elements in universe are H and He
– when stars reach the end of their life cycle,
they spread out C, O, and Fe into the
universe
•
if the universe was older, there would be more C,
O, and Fe