As a comet gets closer to the sun, the size of its tail _______________________.

Bell Ringer

As a comet gets closer to the sun, the size of its tail _______________________.

EXTINCTION OF DINOSAURS, GALAXIES AND

STARS

Effect of Space Debris on Earth Impact Craters form from meteoroid

fragments. The diameter of the crater depends on the size and speed of the meteoroid.

Effect of Space Debris on Earth Much evidence of craters is missing due

to erosion, which DOESN’T destroy the crater evidence on the moon.

Extinction of Dinosaurs (and other species)

The dinosaurs became extinct around 65 million years ago.

In fact, 65% of all species on Earth became extinct at that time.

Extinction of the Dinosaurs (and other species)

The theory is that an asteroid or comet hit Earth, forcing dust into the atmosphere and blocking the sun for years

Extinction of Dinosaurs This may have changed the climate

causing plants to not grow and resulting in the starvation of these species.

Galaxies After the Big Bang, clouds of hydrogen

and helium began forming, which were the beginnings of galaxies.

Galaxies

Galaxies Galaxies are made of billions of stars and

are about 10 billion years old.

Some galaxies, such as the Milky Way are spiral galaxies, resembling pinwheels with huge spiral arms. This galaxy is disk shaped and rotates counter clockwise, taking about 230 million years for one revolution.

Spiral Galaxies

Stars Stars begin as nebula (huge masses of

dust and gas (hydrogen)) that condense in space.

Stars As stars are compressed by gravity the

temperature rises and nuclear fusion begins. Nuclear fusion occurs when hydrogen changes into helium, releasing energy, some as starlight

Stars If these stars explode, they become

supernova.

Stars If these stars collapse inward, they

become black holes.

Star Life Cycle Summary

Star Life Cycle

Our Sun An average star, it rotates on an axis and

is about 5 billion years old. It also will be around for another 5 billion years. Main sequence star- 90% of all stars included

in this group

Our Sun Sunspots are dark spots on the Sun’s

surface that represent cooler gases.

Our Sun These sunspots cycle, hitting a maximum

every 11 years and may affect Earth’s climate when less energy is reaching our planet.