1
00:00:00,500 --> 00:00:03,780
The Sun pumps out energy in all directions 24/7,

2
00:00:03,800 --> 00:00:06,810
and Earth soaks in it every day.

3
00:00:06,830 --> 00:00:08,080
Some of that energy gets absorbed--

4
00:00:08,100 --> 00:00:10,080
by the oceans, the land, the atmosphere--

5
00:00:10,100 --> 00:00:13,980
and some gets reflected back out into space.

6
00:00:14,000 --> 00:00:18,980
How much stays and how much goes is a function of Earth's Energy Budget.

7
00:00:19,000 --> 00:00:21,880
Almost all of Earth's energy comes from the Sun.

8
00:00:21,900 --> 00:00:25,750
As sunlight heats the planet, the planet changes.

9
00:00:25,770 --> 00:00:29,880
The most obvious transformations are with water.

10
00:00:29,900 --> 00:00:31,150
Oceans soak up heat, warming the planet.

11
00:00:31,170 --> 00:00:35,950
But warming water evaporates, which forms clouds.

12
00:00:35,970 --> 00:00:40,580
Those clouds, in turn, reflect sunlight back into space, which cools the planet.

13
00:00:40,600 --> 00:00:45,010
When the clouds dissipate, sunlight once again warms the water below....

14
00:00:45,030 --> 00:00:47,250
...and the cycle continues.

15
00:00:47,270 --> 00:00:49,980
Other areas of the world have similar cycles.

16
00:00:50,000 --> 00:00:52,050
Polar ice caps, for example, reflect sunlight....

17
00:00:52,070 --> 00:00:56,080
...while dark land surfaces soak it up.

18
00:00:56,100 --> 00:01:00,150
Overall, the amount of energy leaving the planet is equal to the amount coming in,

19
00:01:00,170 --> 00:01:04,280
and Earth's energy budget stays roughly in balance....

20
00:01:04,300 --> 00:01:06,380
...and it's a delicate balance.

21
00:01:06,400 --> 00:01:12,080
That's why NASA has missions designed to keep track of how much energy The Sun is putting out,

22
00:01:12,100 --> 00:01:15,110
as well as missions designed to keep track of forces on Earth

23
00:01:15,130 --> 00:01:18,550
that might alter how much heat the planet traps.

24
00:01:18,570 --> 00:01:22,000
That energy balance isn't simply a scientific measurement,

25
00:01:22,020 --> 00:01:25,980
but a description of one of the most fundamental conditions

26
00:01:26,000 --> 00:01:38,980
for making our planet conducive for sustaining life.