Day 3: Sky
Today’s topic is the Earth’s atmosphere and the celestial bodies of outer space.
We’ll start with perhaps the most commonly asked question about the sky—why is it blue? Several other questions are related, about sunrises, sunsets, and the “blue moon”. This reading from the Radio Physics Lab at the Inter-University Centre for Astronomy and Astrophysics summarizes the answers to these questions:
Reading: “Why Is the Sky Blue? (IUCAA-RPL)”
Next we’ll move on to what we mean by the sky: our atmosphere—everything between the ground and the vacuum of outer space.
In the lofty thermosphere is where the “northern lights” manifest—the aurora borealis. NASA gives an overview of this phenomenon:
Reading: “Aurora (NASA)”
Finally, let’s move into outer space! This is the ultimate final frontier of natural history, as we know very little about all the other planets in the world, orbiting around an estimated billion trillion suns in the universe. Of these, about 10,000 can be seen with the naked eye from Earth (assuming no light pollution!).
Video: “The Solar Eclipse in Varanasi (BBC2)” (3:11)
Video: “Space Storms (Nova Science Now)” (10:18 low res)
At some point during this course, learn the phases of the moon, and get accustomed to remembering what phase the moon is in, and what time of day it must be if you see the moon at a particular time in a particular phase.
Get to know your star chart or app in preparation for your time out under the night sky.
Get out and enjoy the night sky! Only some of the nights during this course will be good for stargazing. Keep an eye on the weather and cloud situation, as well as remembering the phases of the moon, and plan your observations accordingly. Full moons rise at dusk and will be fine for looking at the surface of the moon, such as with binoculars or a telescope. Viewing of stars will be best when the moon is dim or absent from the night sky, a time period that peaks when the moon is “new”, and in the same part of the sky as the sun.
By the end of the course, learn, draw and describe in your journal ten constellations.
Try not to look at the night sky as an umbrella-like canvas, but as the far reaches of space extending through our galaxy. Try to notice, if you are in a dark enough area, the Milky Way stretch across the sky. Also look for the planets that are visible along the elliptic on the days you are observing. Venus is the “morning star” and “evening star” that often appears brightly near the horizon as the sun is rising or setting. You can even see the rings of Saturn if you have a 10x or higher magnification on your telescope or binoculars.
~Look not only down and around you, but also up~
A bird came down the walk:
He did not know I saw;
He bit an angle-worm in halves
And ate the fellow, raw.
And then he drank a dew
From a convenient grass,
And then hopped sidewise to the wall
To let a beetle pass.
He glanced with rapid eyes
That hurried all abroad,–
They looked like frightened beads,
I thought; He stirred his velvet head
Like one in danger; cautious,
I offered him a crumb,
And he unrolled his feathers
And rowed him softer home
Than oars divide the ocean,
Too silver for a seam,
Or butterflies, off banks of noon,
Leap, plashless, as they swim.
-Emily Dickinson (1830-1866)
A Light exists in Spring
Not present on the Year
At any other period —
When March is scarcely here
A Color stands abroad
On Solitary Fields
That Science cannot overtake
But Human Nature feels.
It waits upon the Lawn,
It shows the furthest Tree
Upon the furthest Slope you know
It almost speaks to you.
Then as Horizons step
Or Noons report away
Without the Formula of sound
It passes and we stay —
A quality of loss
Affecting our Content
As Trade had suddenly encroached
Upon a Sacrament.
-Emily Dickinson (1830-1866)