Seasons
Seasons
True color images
True color images
June
December
March
What Causes Earth’s Seasons?
What Causes Earth’s Seasons?
Earth’s axis is tilted 23.5 degrees – it always points in
Earth’s axis is tilted 23.5 degrees – it always points in
the same direction (Polaris, the North Star) as we
the same direction (Polaris, the North Star) as we
orbit our Sun once a year
orbit our Sun once a year
This tilt causes the hemispheres to alternate in the
This tilt causes the hemispheres to alternate in the
amount of our Sun’s light and heat they receive
amount of our Sun’s light and heat they receive
through the year
http://www1.teachertube.com/viewVideo.php
http://www1.teachertube.com/viewVideo.php
?video_id=657
More daylight hours and more direct sunlight warms the
Northern hemisphere during the summer months.
Northern Hemisphere
Earth’s orbit is
Earth’s orbit is
almost
almost
a perfect
a perfect
circle
circle
• Earth is
closest
to our Sun (146 million kilometres) in
winter
—January 3 (
Perihelion)
Perihelion)
• Earth is
farthest
from our Sun (151 million
kilometres
)
in
summer
–July 4
(
Aphelion)
Aphelion)
Height of Sun for Canada
Height of Sun for Canada
Winter: The Sun rises in the southeast,
stays low in the sky, and sets in the
southwest.
Spring: The Sun rises due east, moves
higher in the sky than in winter, and sets
due west.
Summer: The Sun rises in the northeast,
travels high (near zenith), and sets in the
northwest.
Daylight Hours Across the Globe
Daylight Hours Across the Globe
Time is indicated as number of hours (h)
Time is indicated as number of hours (h)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 10.5 h 11 h 12 h 12.5 h 13 h 14 h 14.5 h 14 h 12.5 h 12.5 h 11 h 11.5 h
10.5 h 11 h 12 h 12.5 h 13 h 14 h 14.5 h 14 h 12.5 h 12.5 h 11 h 11.5 h
14.5 h 13.5 h 13.5 h 12.5 h 11 h 11 h 11 h 11.5 h 11.5 h 12.5 h 14 h 14.5 h
14.5 h 13.5 h 13.5 h 12.5 h 11 h 11 h 11 h 11.5 h 11.5 h 12.5 h 14 h 14.5 h
12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h
12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h 12 h
17.5 h 15.5 h 13.5 h 11.5 h 10 h 8.5 h 8.5 h 9.5 h 11.5 h 13 h 15 h 16.5 h
17.5 h 15.5 h 13.5 h 11.5 h 10 h 8.5 h 8.5 h 9.5 h 11.5 h 13 h 15 h 16.5 h
5 h 7 h 10 h 13.5 h 17.5 h 21.5 h 22 h 18 h 15.5 h 11.5 h 8.5 h 5.5 h
5 h 7 h 10 h 13.5 h 17.5 h 21.5 h 22 h 18 h 15.5 h 11.5 h 8.5 h 5.5 h
12 h 12 h 12 h 12 h 13 h 13 h 12 h 12 h 12 h 12 h 12 h 12 h
12 h 12 h 12 h 12 h 13 h 13 h 12 h 12 h 12 h 12 h 12 h 12 h
15 h 14 h 13.5 h 12.5 h 11.5 h 10 h 10.5 h 11 h 11.5 h 12.5 h 14 h 14 h
15 h 14 h 13.5 h 12.5 h 11.5 h 10 h 10.5 h 11 h 11.5 h 12.5 h 14 h 14 h
9 h 10 h 11 h 13.5 h 15 h 17 h 16.5 h 15.5 h 13.5 h 11.5 h 10.5 h 9.5 h
9 h 10 h 11 h 13.5 h 15 h 17 h 16.5 h 15.5 h 13.5 h 11.5 h 10.5 h 9.5 h
24 h 24 h 19 h 14.5 h 0 h 0 h 0 h 0 h 7 h 15 h 24 h 24 h
Seasons on Other Planets
Seasons on Other Planets
In some cases, the
In some cases, the
changing distances
changing distances
from the Sun will
from the Sun will
affect the seasons.
affect the seasons.
In others, the axial tilt
In others, the axial tilt
will make a huge
will make a huge
difference!
http://www.dailymotion.com/vi
http://www.dailymotion.com/vi
deo/x6k6c0_what-is-a-solstice
deo/x6k6c0_what-is-a-solstice
_people
Seasons on Planets
Seasons on Planets
Planet
Planet
Axial Tilt Eccentricity Orbit
Axial Tilt Eccentricity Orbit
Perihelion Aphelion
Perihelion Aphelion
of Orbit
of Orbit
(closest)
(closest)
(furthest)
(furthest)
Mercury
Mercury
0°
0°
0.21
0.21
88 days 45 million km 69 million km
88 days 45 million km 69 million km
Venus 177°
Venus 177°
0.01
0.01
224 days
224 days
Earth
Earth
23.5°
23.5°
0.02
0.02
365 days 146 million km 151 million km
365 days 146 million km 151 million km
Mars
Mars
25°
25°
0.09
0.09
686 days 208 million km 249 million km
686 days 208 million km 249 million km
Jupiter
Jupiter
3°
3°
0.05
0.05
12 years
12 years
Saturn
Saturn
27°
27°
0.06
0.06
30 years
30 years
Uranus
Uranus
98°
98°
0.05
0.05
84 years
84 years
Neptune 30°
Mars’ Orbit and Seasons
Mars’ Orbit and Seasons
At summer solstice, Mars
is 153 million miles from
the Sun
At winter solstice, Mars
is 128 million miles
from the Sun
