Reports - 2013

Pictures from the Hubble Site

Astronomy Benalla  Meeting Presentations - Wednesday 15th May 2013 Presenter: Patrick Watson WHERE ON EARTH IS OUR HYDROGEN? CHEMICAL ABUNDANCE  IN THE UNIVERSE Helium is about 25% by mass and hydrogen about 73% with all other elements constituting less than 2%. It is clear then that hydrogen and helium make up 98% plus of the ordinary matter in the universe. But not on Earth! EARTH Composition of dry atmosphere, by volume We commence by asking a second question: What is the average speed of a hydrogen molecule (H₂) at (SAY) room temperature , 20 C? Boltzmann Constant = 1.38 x 10^-23 J/K 0^oC = ≈273 K.      So,   20^oC = (273 + 20) = 293 K Mass of a hydrogen molecule = mass of a hydrogen atom x 2  = 3.4 x 10^-27 kg Now we know that In some situations, atoms and molecules in a gas may be moving so fast that they can overcome the attractive force of a planet’s gravity and escape into interplanetary space. ESCAPE SPEED SO???? SO??? A good rule of thumb is that a planet can retain a gas if the escape speed is at least 6 times greater than the average speed of the atoms or molecules. SO - WHERE ON EARTH IS OUR HYDROGEN  ->  HYDROCARBONS! A hydrocarbon is an organic compound consisting entirely of hydrogen and carbon.  Methane  Ethane  Propane  Butane  Etc., etc., etc.,