Earth and the Sun

Earth and the SunEarth Science 2013

Astronomy

• Definition: The study of the planets,[------ moon, stars, and other objects in space

Astronomy

Sun

• The Sun is the center of our Solar System• There are 8 planets in our solar system• We are 92 million miles from the Sun• The Sun is responsible for all the energy we

receive on Earth

The Sun

Earth • The planet we live on• Only Planet with life(that we know of…)• Third planet from the Sun

Earth • The Earth is an inner planet– Small in size– Few or no moons(only one)– No rings

Earth’s Movements• Rotation: One spin on its axis• Takes about 24 hours to rotate once• This rotation causes DAY and NIGHT• Sun always rises in the EAST and sets in the

WEST

Earth’s Movements

• Revolution (orbit): One lap around the Sun• This takes about 365 days or one year to

complete• The path is not quite a circle; its more of an

oval shape

Calendars• Calendars mark time on earth in 24 hour days

and 365 days per year• The Egyptian astronomers counted the days

between the appearance of the star Sirius and found an average of 365 days between appearances.

• So the Egyptians came up with one of the first Calendars!

Leap Years• The path of the Earth around the Sun actually

takes 365 ¼ day to complete.• Every fourth year we add up the extra time

¼ + ¼ + ¼ + ¼ = one extra day• This day is added to the calendar every 4 years

on February 29• Leap Years: 2004, 2008, 2012, 2016, 2020,

2024, 2028, etc

Earth’s Tilt

• Earth has seasons because the axis is tilted as it moves around the Sun

• WE ARE IN THE NORTHERN HEMISPHERE• When the Northern Hemisphere is tilted

towards the Sun, we get the most sunlight = summer

• When the Northern hemisphere is tilted away from the Sun, we get the least sunlight = winter

Seasons

Seasons

• Most places on Earth have 4 distinct seasons: Winter, Spring, Summer, and Fall

• The length of each season depends on its location on the Earth and how the sunlight hits the Earth

• The uneven heating of the Earth creates three different climates: tropical, temperate, and polar

Season’s interactive

• Click here

Four Seasons

• Winter Solstice– Starts around December 21– Northern Hemisphere is tilted away from the Sun– The rays from the Sun are the weakest– Shortest day of the year in Northern Hemisphere;

longest day of the year in the Southern Hemisphere

– Marks the beginning of winter

Four Seasons

• Autumnal Equinox– Starts around September 22– The Suns is directly over the equator creating an

equal amount of daytime and nighttime – Marks the beginning of Fall

Four Seasons

Four Seasons• Spring Equinox– Starts around March 21– The Suns is directly over the equator creating an

equal amount of daytime and nighttime – Marks the beginning of summer

Four Seasons

• Summer Solstice– Starts around June 21– Northern Hemisphere is tilted towards the Sun– The rays from the Sun are the strongest– Longest day of the year in Northern

Hemisphere; shortest day of the year in the Southern Hemisphere

– Marks the beginning of the summer

Four Seasons

Climate Zones

The Moon

• The Moon takes 27.3 days to revolve around the Earth

• The Moon takes 27.3 days to rotate on its axis

• Therefore, we only ever see one side of the moon

Lunar Landing Sites