The night sky has always been humanity's most ancient time clock. The movement and absence of
the sun guides the day and the night. The months are measured by the phases of the moon and every
season begins with a solstice or Equinox. As the Autumn season approaches in the Northern
hemisphere the days grow shorter the nights become longer until we meet the days of the Autumn
Equinox, also called the fall equinox. In this video we will explore the concept of the Autumn
Equinox, why it happens, and how the star patterns in the night sky will shift as the seasons change.
Welcome to Learn the Sky, my name is Janine and I'll be your guide as we
explore the night sky together one constellation at a time.
What is the Autumn Equinox? The Autumn Equinox is considered the first day of Autumn or Fall and
one of the two days of the year in which the day and night are of equal length. If you break down
the word Equinox it comes from the Latin word 'Aequi' which means equal, and 'nox' which means night. The
word Autumn is also derived from Latin, but its roots are a bit obscure. The earliest versions
of the word Autumn were called Harvest, however records of the word Autumn surfaced in the 1300s
and works of Chaucer and Shakespeare, and the word fall shows up about 200 years later. So the use of
Autumn or Fall or Harvest for this season depends upon the culture in place, but if you can recognize
the root words of the Autumn Equinox it can help you remember that it is the time of year where the
day and the night are of equal length, marking the first day of the Fall. From the celestial point of
view an equinox event is when the Earth's tilt and orbit around the Sun align its axis neither away
from the Sun, nor towards the Sun. During this time the Sun shines directly on the earth's equator. For
the Autumn Equinox this date usually occurs after mid-september and it marks the first day of Autumn.
The first Equinox happens earlier in the year after mid-march and it marks the first day of
spring. The experience of the Autumn Equinox will be different depending on which hemisphere you
live in. I'm located in the Northern hemisphere, so for us the Sun is rising later now and nightfall
comes earlier. The temperatures begin to cool, and the days start to get shorter, and the nights get
longer. The trees and plants are ending their cycle of growth and it's like Nature's last
blast of energy before the winter comes. Meanwhile, south of the Equator they experience the opposite
effect. Life everywhere is beginning to reawaken after having the longer nights and shorter days.
From the stargazer's perspective, the star patterns and celestial objects begin to shift as well. The
Milky Way is no longer present in the sky during the Autumn months, and this allows
us to peer deeper into the universe. Fall time provides an awesome opportunity for us to see
far away galaxies, but sometimes you often need magnification if you want to see these distant
galaxies. The exception to this would be the Andromeda galaxy. This is a fuzzy patch in the sky
that will be the oldest light you would ever see with the naked eye. Andromeda galaxy is a distant
spiral galaxy, and it's speeding towards our own Milky Way galaxy and it really is an awesome
object to see either with the naked eye or with magnification. The constellation patterns we see in
the night sky begin to shift as well. Some of the main constellations you can see during this time
are Pegasus, Andromeda, Perseus, Triangulum, Capricorn, Aquarius, Delphinus, and Aries. So this concludes our
video about the Autumn Equinox. No matter where you are on the planet we share this day together as
the seasons change. Thank you so much for watching and let me know in the comments what is the Autumn
Equinox like in your area of the world. For me personally I love autumn because of the seasonal
changes it brings. It's just cooler, the leaves change color and apples and pumpkins are ready to
be picked. It's definitely my favorite season. So I know this community of star gazers includes
people all around the world, so feel free to share your unique experiences, and as always I encourage
you to go outside view the stars. Take a friend or pet with you, and as always keep looking up.