1.4 Earth-Sun-Moon Interactions Flashcards
Why don’t solar eclipses happen every month?
The plane the moon orbits on doesn’t match the ecliptic.
What is conjunction?
An alignment of two planets or other celestial objects so they appear to be in the same or nearly the same place in the sky.
Why is the moon visible?
It reflects sunlight.
What are Baily’s Beads?
Small bright spots of sunlight caused by the Sun’s rays shining through valleys on the Moon.
How long is a sidereal day?
23 hours and 56 minutes.
Why do the sun and the moon appear to be the same size in the sky?
The angular size of the sun and moon are the same size from Earth.
Describe a total eclipse.
- Occurs at a new moon.
- The moon passes directly in front of the sun.
- Light from the suns photosphere is obscured if the observer is in the umbra.
Describe a partial solar eclipse.
When the moon only partly obscured light from the sun.
What is a lunar eclipse?
- Occurs at full moon.
- It’s when the Earth passes between the sun and the moon.
- The moon gives a reddish glow.
Why does the moon appear red during a lunar eclipse?
“Blues bend best.” Light from the sun is refracted by the earths atmosphere.
What is a sidereal day?
The actual time it takes for the Earth to spin 360° on its axis.
What is a solar day?
The time taken for successive crossings of the sun across the observers meridian. This is an extra 4 minutes longer than the sidereal day because the Earth has moved slightly on its orbit from its original position.
