1. of Montgomery College Planetarium
The REAL OCCULT:
Lunar & Solar Eclipses and Asteroid & Stellar Disappearances Sometimes Involving Luna
By Dr. Harold Williams
of Montgomery College Planetarium
Sunday, September 27, PM
Title slide

2. Types of Occultations Lunar Eclipse, Solar Eclipse,
Asteroidial Occultation,
Lunar Occultation,
Grazing Lunar Occultation
Planet Lunar Occultation
Transit of Planet across the Sun
Transit of Mercury (next one November 8, 2006)
Transit of Venus (June 8, 2004, next one June 6, 2012)
Planet disappearing behind moon
Classification of occultation opportunity.

3. Lunar Eclipse
Lunar Eclipse, shadow of the earth gets in front of the full moon at night time.
When the moon, earth, and sun align in that order at a node.
The reason we do not have 13 eclipses a year is because the orbit of the earth around the sun, the ecliptic, and the orbit of the moon around the earth are inclined by around 5 degrees, they are not aligned (it would be improbable if they were perfectly aligned instead of being close).

4. A Total Lunar Eclipse
Foundations of Astronomy 8th edition by Michael A. Seeds

5. A Total Lunar Eclipse
A total lunar eclipse can last up to 1 hour and 40 min.
During a total eclipse, the moon has a faint, red glow, reflecting sun light scattered in Earth’s atmosphere.
Foundations of Astronomy 8th edition by Michael A. Seeds

6. Lunar Eclipses
Earth’s shadow consists of a zone of partial shadow, the Penumbra, and a zone of full shadow, the Umbra.
Foundations of Astronomy 8th edition by Michael A. Seeds
If the moon passes through Earth’s full shadow (Umbra), we see a lunar eclipse.
If the entire surface of the moon enters the Umbra, the lunar eclipse is total.

7. Lunar Eclipse on the Earth seen from the moon
Painting by Lucien Rudaux, (1874 – 1947)showing what a lunar eclipse might look like when viewed from the surface of the moon. The moon's surface appears red due to the fact that the only sunlight available is refracted through the Earth's atmosphere on the edges of the earth, as shown in the sky in this painting.

8. Danjon Scale for Lunar Eclipses
0 Very dark eclipse. Moon almost invisible, especially at mid-totality.
1 Dark Eclipse, gray or brownish in coloration. Details distinguishable only with difficulty.
2 Deep red or rust-colored eclipse. Very dark central shadow, while outer edge of umbra is relatively bright.
3 Brick-red eclipse. Umbral shadow usually has a bright or yellow rim.
4 Very bright copper-red or orange eclipse. Umbral shadow has a bluish, very bright rim.

9. Eclipse visibility

10. Rarity of Tonight‘s Event
"Since Year 1, I can only find one previous instance of an eclipse matching the same calendar date as the solstice, and that is 1638 Dec. 21," says Geoff Chester of the U.S. Naval Observatory who inspected a list of eclipses going back 2000 years. The next one happens near the end of this century in 2094.

11. In case of Clouds

12. Solar Eclipse
Solar Eclipse, new moon gets in front of the sun in the day time.
When the earth, moon, and sun align in that order at a node.
The reason we do not have an eclipse every month is again, because of the 5 degree inclination of the orbit of the earth around the sun and the orbit of the moon around the earth.
Fred Espenak's Eclipse Pages at best general scientific source of eclipse maps, dates, and general data for both lunar and solar eclipses. Everyone uses Fred Espenak, he is without peer for specific eclipse information.
Wendy Carlos Eclipse Pages at , some of the finest pictures taken by a true artist of solar eclipses and music.

13. FIGURE 3-1 in Foundations of Astronomy 8th edition by Michael A. Seeds
(a) A 12th-century Mayan symbol believed to represent a solar eclipse. The black-and white sun symbol hangs from a rectangular sky symbol, and a voracious serpent approaches from below.

14. Diamond Ring Effect
Foundations of Astronomy 8th edition by Michael A. Seeds

15. Solar Atmosphere Revealed
Foundations of Astronomy 8th edition by Michael A. Seeds

16. Solar Eclipses
Foundations of Astronomy 8th edition by Michael A. Seeds
The sun appears approx. as large in the sky (same angular diameter ~ 0.50) as the moon.
 When the moon passes in front of the sun, the moon can cover the sun completely, causing a total solar eclipse.

17. Solar Eclipse Viewing Safe Solar Filters
While lunar eclipses are inherently safe, Solar Eclipses, the partial phases, are of course dangerous to human eyes. Of course, they are no more dangerous than looking at the sun on any day time that the sun is visible. Toddlers and grasshoppers avoid blinding themselves every day when the sun is visible by not looking directly at it.
If it hurts don't do it.
Safe Solar Filters

18. Solar Filters Places to get safe solar filters
or Hands on Optics in Damascus, MD 20872, . During the total solar eclipse though it is quite safe to look directly at the sun. I have spent a total of 4 minutes looking directly at the sun during two total solar eclipses; and it has not damaged my eyes.

19. Earth and Moon’s Orbits Are Slightly Elliptical
Apogee = position furthest away from Earth
Earth
Perihelion = position closest to the sun
Moon
Perigee = position closest to Earth
Foundations of Astronomy 8th edition by Michael A. Seeds
Sun
Aphelion = position furthest away from the sun
(Eccentricities greatly exaggerated!)

20. Annular Solar Eclipses
When Earth is near perihelion, and the moon is near apogee, we see an annular solar eclipse.
The angular sizes of the moon and the sun vary, depending on their distance from Earth.
Foundations of Astronomy 8th edition by Michael A. Seeds
Perigee
Apogee
Aphelion
Perihelion

21. Annular Solar Eclipses
Foundations of Astronomy 8th edition by Michael A. Seeds
Almost total, annular eclipse of May 30, 1984

22. Conditions for Eclipses
The moon’s orbit is inclined against the ecliptic by ~ 50.
Foundations of Astronomy 8th edition by Michael A. Seeds
A solar eclipse can only occur if the moon passes a node near new moon.
A lunar eclipse can only occur if the moon passes a node near full moon.

23. Conditions for Eclipses
Eclipses occur in a cyclic pattern.
Foundations of Astronomy 8th edition by Michael A. Seeds
 Saros cycle: 18 years, 11 days, 8 hours

24. Asteroidial Occultation
An asteroid orbiting the sun sometimes get in front of a star as seen from the earth.
This type of Asteroidial occultation is used to measure the size of the asteroid
and to tell whether it has an any moons orbiting the asteroid.
Here the alignment is earth, asteroid, and star in that order.

25. 29 October Pretoria

26. Asteroidial Occulation Updates

28. Lunar Occultation
Moon traveling in it orbit around the earth occults stars.
When it occurs near the top or bottom of the moon this is called a Grazing Lunar Occultation. As the star gazes behind the lunar edge profile the star appears to go out and then back on when it appears from a deep lunar valley.
Grazing lunar occultations are used to determine the lunar edge profile very accurately so that when solar eclipses happen and the last part of the photosphere appears in deep lunar valleys, forming Baily's Beads. The timing of these Baily's beads can be used to tell whether the sun is getting larger or smaller over time, by comparing Baily's beads timing from solar eclipse to solar eclipse. This is basic long term research that answers extremely important critical questions about the size of the sun and future changes in our climate on earth. Global warming or cooling and all of that sort of stuff.
Moon can get in from of a planet like Saturn (seen it).

29. Lunar Occultation Links

30. February 20, 2002 Moon occults Saturn
Astronomy Picture of the Day February 22, 2002.

31. Transist of Venus Across the Disk of the Sun June 8, 2004
Transit of Mercury across the disk of the sun November 8, 2006.
Visibility of June 6, 2012 transit of Venus across the Sun.