1. Physics Assignment Galaxy Research
4/24/2019

2. 1) How many known galaxies are there?
2) How many stars on average are in a galaxy?
3) How far away is the next galaxy?
        a) In AUs?         b) In Parsecs?         c) In Miles?
4) What is an exoplanet? 5) How many known exoplanets are there? 6) What is an exoplanet's "goldilocks zone"? 7) How many exoplanet systems have been found?
8) What is the percentage of stars that are thought to have exoplanets? 9) Calculate the number of estimated planets in the Universe.
What is the overall probability that there is life somewhere else in the Milky Way galaxy (use facts to back up your answer such as amount of known exoplanets, amount of predicted exoplanets, age of planets compared to Earth, how quickly life on earth started.  Backup your probability with an explination) ?
What is the probability that there is life somewhere in the Universe? 

3. 1) 100,000,000,000
2) 100,000,000,000
3) a) 139,100,000,000 AU's  b)  c) 1,293,000,000,000,000,000
4) A planet that circles another star other than our own
5) 4023
6) 30
7) 3,005
8) 75%
9) 100,000,000,000 * 100,000,000,000 * .75 = 7,500,000,000,000,000,000,000
Of the 3,800 Exoplanets researched so far by the Planetary Habitability Laboratory at University of Puerto Rico they have found 49 to be in the "Habitable" or "Goldilocks" Zone.  These are planets that have just the right size and just the right distance from their respective stars.  That gives us a ratio of 49:3800 or 1.2%.  There is an estimated 250,000,000 stars in the Milky Way galaxy.  Of these it is estimated that 75% have at least 1 exoplanet.  With 1.2% in the Habitable zone that would give 3,000,000 planets in the Milky Way that would be in the right area for life.  However, using very low estimates let's say that 99% of those have had one or more astronomical disasters, such as large meteor collisions, massive gravity anomalies, or have had runaway greenhouse atmospheres; that would leave us with 30,000 planets in the Milky Way that could have life.  Life on our planet started when our planet was about 1,000,000,000 years old and has continued for the past 3,500,000,000 years.  Let's say that life had started on other planets, but a disaster struck and had to restart.  If only 1% of planets were able to recover, I would estimate that there would be about 300 planets that have life.  That is 0.0075% of planets in our Milky Way.
Making the same assumptions for the entire Universe that would give us 7,500,000,000,000,000,000,000 * = 562,500,000,000 planets in the Universe that would have a good possibility of life.