Notes from shiur on astronomy- Rabbi Chaim Friedman 1/1/13

1. earth is 7,964 miles in diameter approx
2. moon is 2,164 miles in diameter approx
3. the moon is 389.000 miles from earth approx
4. THE SUN IS 400 BIGGER THAN THE MOON AND 400 TIMES FURTHER AWAY FROM EARTH THAN THE MOON SO THEY LOOK SAME SIZE FROM EARTH.
5. WHEN THE MATCH UP YOU GET THE ‘MOLAD’
6. You need to wait a day or so till the sun moves past the moon and you can see the moon.
7. There is always 29 days 12 hours 44 minutes and 1 chelek (3.3 seconds) between molads
8. So basically add 1 day, change am to pm or vise versa and add 44 minutes to molad and you get next molad.

The Zodiacs are a group of stars that orbit the earth every day. Each takes 2 hours to pass the earth. The group of stars form a picture – hence Adar is known as a fish cos the constellation looks like a fish.

The constellations move slightly faster than the sun so when the sun rises at the start of the ‘fish constellation’ it is the month of adar. On day 30 it rises next to the bottom star.

The next month it rises next to the head of constellation of Nissan and so on and so forth .

The sun does not rise in the same place every day. It moves from north to south.

Seforno in Noach says this was after flood cos before that everyday was equal like spring.  This does not fit in with gemoroh  in Avodoh Zorroh daf 8a which says Adam saw the days getting shorter……

There are 4 Tekufot

Tamuz- when the sun reaches its northern most point of rising- hence giving most daylight to the north and its summer.

Teves- when the sun is at its southern most point of rising 2 equinoxes when the sun rises exactly over the equator – tishrei a