Lesson Plan # 5

Aim: The solar system and its properties

Vocabulary: heliocentric theory, solar system, Terrestrial planets, Jovian planets, rotations, moons, comets, meteoroids, asteroids, greenhouse gas affect

Discussion: Yesterday we discussed the way our planet moves through the space in orbit around the sun which is called the heliocentric theory. Today we will learn about the other objects in our solar system.

Motivation: How many planets are there in the Solar system according to Chazal? 7. All the poskim write that the Torah only deals with things that are nireh laynaim and therefore if Chazal didn’t mention any more it’s because you can’t see it without the aid of any other devices.

1) Scientists divide Planets into two types terrestrial or rocky planets such as all four first planets (Mercury, Venus, Earth, Mars) and Jovian or Gas (Jupiter, Saturn, Neptune, Uranus) planets with no or little rock on them.

2) These Jovian planets, despite their humongous size, are only a quarter as dense as earth is. Earth is a very dense rocky planet with a density of 5.5 g/cm3.

3) Now lets examine the other planets a little more in depth. Mercury is the planet closest to the sun and is very hot and has no atmosphere. This fact has left that planet with many marks on it from the thousands of meteorites that have slammed into it over time. It is similar to the moon in this way as they both have extremes in temperature (why? Because all the heat escapes it on the side that is not facing the sun since the atmosphere keeps in heat) and also have slow days due to their slow rotations. Venus even though further than mercury from the sun is hotter since its atmosphere locks away all the heat in an uncontrolled greenhouse gas affect from the sun. Earth and mars are cooler since we are further away yet mars is even cooler than earth. The gas giants do not have much surface if any and the heat in them increases with depth. Pluto is very very cold and has recently been declassified as a planet.

4) Earth is unique. It is the only planet with an abundance of water that allows for life to exist. [M1] It also is unique that its atmosphere has lots of oxygen which supports life. The US government spends lots of money on space exploration trying to understand our own planet and trying to explore the possibility of resource extraction and possible colonization.

5) Asteroids- these are small to large rocks located between mars and Jupiter in what’s called the asteroid belt. They range in size between 600 kilometers wide to the size of a small pebble. There is evidence that many years ago a massive asteroid struck earth in the Yucatan peninsula and possibly caused a massive dust cloud which wiped out all the dinosaurs by starving them out with most other forms of life on the planet.

6) Meteors[mb2] are solid objects (pebbles) that are pulled into the orbit of earth by earth’s gravitational pull. They usually enter the atmosphere and are burnt up and producing a spectacular shower of light in the process. Sometimes these objects do survive and they are called meteorites.

7) Comets[M3] -are icy objects that come from outside the solar system and swing in highly elliptical orbits around the sun. The most famous comet Halley’s Comet comes every 75 years. As they swing around the sun the ice partially melts the ice and the remnants trail behind this ball of ice as a tail of the comet. Unlike meteors which last for a brief moment comets can be visible for weeks at a time.

[M1]Just take a moment at marvel at the uniqueness of Earth in the Solar system and in the known Universe as a matter of fact. How grateful we must be to the master of the Universe for making such beauty in a vast space of nothingness, and then marvel at the foolishness of those that say that the world in all its multiple ways is a pure coincidence!

[mb2]The gemara says in moed katan 16a that barak is a name of a star (probably a mteorite) that came down and killed the goyim in milchemes sisra.

[M3]See the Gemara in Bearchos (58b) where it mentions something called a Kochva Dishavet which Rash”I seems to interpret as a comet