To ASTRONOMY….. and beyond!

What we will be discovering:

Structures of the solar system The Sun-Earth-Moon System The Planets and their Moons Asteroids, Comets, and Meteoroids Stars and Galaxies

Axis and Period of Rotation

Axis of Rotation Period of Rotation

an imaginary line that runs through the center of the planet. (The planet rotates around this line.)

The time it takes for one rotation around the axis to occur. (one day)

Period of Revolution and Ellipse

Period of Revolution Ellipse

The time it takes a planet to move completely around the sun. (one year)

Oval shaped. (example: Earth’s orbit around the sun is an oval or ellipse.)

ALL planets have elliptical orbits around the sun (Kepler’s first law)

AU’s and LY’s

Astronomical Unit

The average distance from Earth to the Sun.

1 AU = 149,600,000km

The distance that light travels in a vacuum in one Julian year. (365.25 days)

Typically used to measure distances on a galactic scale.

1 ly = apx 10 trillion km

Light Year

Now, because I know you’re interested…

Revolution and Rotation

periods of the planets:Planet P of rotation P of revolution

Mercury 59 days 88 days

Venus 243 days 255 days

Earth 24 hours 365 days

Mars 24 hours 687 days

Jupiter 10 hours 11.9 years

Saturn 11 hours 29.5 years

Uranus 17 hours 84 years

Neptune 16 hours 165 years

The reason for the seasons!

The yearly cycle of the seasons is caused by the tilt of Earth’s axis as it revolves around the sun.

Depending on which hemisphere is tilted towards the sun, they will be experiencing summer and the one tilted away will be experiencing winter.

The equator always experiences warm weather because it’s always tilted toward the sun!

Earth + Revolution = Seasons

The Equinoxes

The earth experiences 2 equinoxes- one in March and one in September.

An equinox is when neither end of the Earth’s axis is tilted toward the sun, therefore, both hemispheres are receiving an equal amount of sunlight and energy!

Day and night are equal in length during the actual equinox (March 21 and September 22)

The Solstices

The solstices are the times of year when the direct sunlight is farthest north or south of the equator.

The summer solstice occurs for us on June 21 (this is the winter solstice for the southern hemisphere)

The winter solstice occurs for us on December 21 (this is the summer solstice for the southern hemisphere)