Full transcript
0:00however we can actually get different
0:04types of eclipses as well in the case of
0:07a solar we can have a total solar
0:09eclipse where you can see these Sun is
0:11really blocked out in this case we're
0:13only seeing the outer regions of the Sun
0:15we'll talk more about that in chapter 9
0:17but this is say the chromosphere the
0:20outer regions the actual Sun is being
0:21blocked we can also have a partial solar
0:24eclipse where you can see only a part of
0:26it's blocked the moon only blocks it
0:28partially and finally the annular
0:32eclipse and you can the annular annular
0:34stands for ring so annular eclipse well
0:37not the entire Sun is blocked in fact
0:40this image shows a pretty spectacularly
0:42there's still a ring of the Sun around
0:45the moon you see that looks quite a bit
0:48difference than the total case where
0:50this is the outer regions this is still
0:52a very well-defined Sun that you can
0:56still partially see in the case of an
0:57annular eclipse but why well it actually
1:03has to do with the moon's orbit remember
1:07talking about angular size the moon
1:09happens to have the same rough angular
1:11size of the moon the thing is the moon
1:14is not at a fixed distance from us the
1:18moon's distance from us changes slightly
1:20from one time to the other just like our
1:23orbit around the Sun changes slightly
1:25from one time to another so depending on
1:27those conditions sometimes the moon
1:30might be a little bit closer to us and
1:32thus have a bigger angular size and thus
1:35block more of the moon or if it so
1:38happens that it's further away from us
1:41in the case that they call Apogee Apogee
1:43for further away or perigee for when
1:45it's nice and close if we have an
1:48eclipse when the moon's at Apogee we
1:50will get an annular eclipse because it
1:53doesn't block out the entire Sun for us
1:56in fact you can see it shows that the
2:00actual inner region that Umbra of the
2:03Eclipse the Umbra of the moon's shadow
2:06wouldn't reach earth in that case now we
2:10can also have the
2:13total eclipse here where you can see it
2:15actually is large enough to block it out
2:17the Sun or the partial eclipse the
2:20partial eclipse is when we from our
2:23perspective don't see the Umbra the
2:26inner shadow it's possible you could
2:28have some people see the total eclipse
2:30but anyone further away at an angle to
2:34that or that a different point to that
2:35would actually see only a partial
2:38eclipse because they're not within the
2:40inner shadow you have to be within that
2:42Umbra region to see the total eclipse
2:44otherwise you only get a partial one and
2:47this also image shows nice example of
2:50the difference in size of the moon from
2:51Apogee to perigee so it can be pretty
2:54significant and thus again impacts the
2:56angular size and how much of our Sun
2:59would be blocked out during eclipse of
3:02course you might be wondering wait why
3:06aren't we always having an eclipse if it
3:08only takes the moon being between us and
3:12the Sun or us being between the Sun and
3:16the moon well that happens every month
3:19we looked at that with the phases New
3:21Moon's full moons those happen once a
3:23month well the thing to keep in mind
3:26something we haven't discussed right now
3:28is the orbit of the moon around us is
3:32actually inclined relative to our path
3:36around the Sun so it doesn't always line
3:41up what do I mean well in many cases and
3:45it's important to note by the way we
3:46don't have two moons as just showing
3:47both possible cases here well in many
3:51cases let's say we get this situation
3:53where we have a new moon so the moon's
3:55between us and the Sun well because of
3:58this 5 degree roughly and inclination of
4:02the moon's orbit around us sometimes it
4:06might be above or below us you can see
4:08in this case it's actually below the
4:11line between us and the Sun so the
4:13shadow it casts actually goes under
4:16earth or in this case over here the
4:18shadow goes above earth or if we were
4:21looking at a full moon we'd have our
4:24shadow pass
4:26under the moon or over the moon it's
4:30only in those cases where we are not
4:33only lined up but the moon is passing
4:36across the ecliptic and thus the moon
4:40the earth and the Sun are all lined up
4:43when that happens on either a new or a
4:45full moon then we'll get one of those
4:48eclipses but they don't happen all the
4:50time simply because of this 5 degree or
4:54roughly 5 degree inclination so often
4:58the moon doesn't line up perfectly
5:00between us and the Sun or it doesn't
5:02line up perfectly behind us in the Sun
5:05so in those cases we won't get into
5:08clips will me in these clay cases right
5:11here and the thing is we have this well
5:19plotted we know the motion of the moon
5:22we know the motion of Earth around the
5:24Sun so we can predict these eclipses to
5:27a very high degree of accuracy in fact
5:30recently we had the 2017 eclipse it was
5:34well known well publicized in fact we
5:36would have an event down at the
5:37waterfront cuz we knew it was coming but
5:40we can predict these all the way out you
5:43can see even to 2000 or to 2040 right
5:46here this shows it and if you want you
5:49can look at our appendix appendix H in
5:52the book it lists a bunch of the
5:53different eclipses that will be
5:54occurring and ones that you might be at
5:56a view and for anyone who's in Windsor
5:59and might be in Windsor for the
6:01foreseeable future especially look at
6:03the one in 2024 it's actually this blue
6:06line right here and you can see it's
6:08gonna actually pass right by Windsor
6:12this is a solar eclipse this will be a
6:14total solar eclipse I believe the last
6:18recent one we had again we were pretty
6:20lucky in 2017 we got a partial eclipse
6:23in Windsor roughly about 80% of Sun
6:26blocked this one I think from windsors
6:29perspective we'd see something like 99%
6:31of it blocked and if you went to Point
6:33Pelee you would witness the total solar
6:37eclipse
6:38so worth keeping an eye out for