WEBVTT

1
00:00:00.600 --> 00:00:02.290
Why is it summer in June?

2
00:00:02.740 --> 00:00:06.349
Most people say: because the Earth is
closer to the Sun.

3
00:00:07.449 --> 00:00:12.069
It sounds right. But we are closest to the
Sun in early January,

4
00:00:12.069 --> 00:00:13.946
and farthest away in July.

5
00:00:14.396 --> 00:00:17.861
The distance changes by only about three
per cent.

6
00:00:18.761 --> 00:00:22.572
So distance is not the answer. The answer
is the tilt.

7
00:00:24.672 --> 00:00:28.177
This is the Earth in June. Its axis is
tilted,

8
00:00:28.177 --> 00:00:30.920
and the north leans towards the Sun.

9
00:00:31.370 --> 00:00:35.676
Sunlight hits the northern half more
directly, and the days are longer.

10
00:00:36.126 --> 00:00:37.667
That is summer in the north.

11
00:00:39.667 --> 00:00:43.413
Six months later, the Earth is on the
other side of the Sun.

12
00:00:43.863 --> 00:00:47.104
Watch the axis. It still points the same
way.

13
00:00:47.104 --> 00:00:49.841
Now the north leans away from the Sun.

14
00:00:50.291 --> 00:00:55.416
The light arrives at a low angle and
spreads out. That is winter in the north.

15
00:00:57.216 --> 00:00:59.037
Put the whole year together.

16
00:00:59.037 --> 00:01:03.263
The axis keeps pointing in the same
direction, all the way round.

17
00:01:03.713 --> 00:01:08.751
In June, the north leans towards the Sun.
In December, it leans away.

18
00:01:09.951 --> 00:01:13.521
So it is not about being closer. It is
about the tilt.

19
00:01:14.421 --> 00:01:18.653
Now pause the video, and draw the Earth in
June and in December.