Stars sizes

1. How would you rank the following according to their size (starting with the smallest): A galaxy, a planet, a star, solar system, a galaxy cluster. Share where you found your information.
2. Which of the objects in #1, if any, are within a 1 light-year radius from Earth? More than 1 light-year, but within 100 light-years?
3. Share one interesting fact or explanation from your readings this week that illustrates the vast size of the universe. Explain why this strikes you as interesting.

(smallest to largest) Diameter
1.) Planet (Earth) Earth's Circumference at the Equator: 24,901.55 miles (40,075.16 km); Earth's Diameter at the Poles: 7,899.80 miles (12,713.5 km); Earth's Circumference Between the North and South Poles: 24,859.82 miles (40,008 km) [1]

2.) Star (Sun) 1,392,000 KM (865,000 MI.) [1]

3.) Solar System Sun to Pluto (dwarf planet) 78.88 AU; Sun to end of Oort Cloud 100,000 AU [1] Oort cloud starts at 50,000 AU AU stands for Earth-Sun distance.
4.) Galaxy 4 billion, 8 thousand, 3 hundred, and 29 miles big or 100,000 lightyears diameter [1][2][3]

5.) local group cluster 3,000 kiloparsecs (10 million light years) diameter [1]

6.) Virgo Cluster (galaxy supercluster) 15 million light years diameter [1]


2.) All the planets or dwarf planets that don’t pass Pluto, and the Sun are all within a light year. I read the true distance of the solar system is 2 light years in distance that includes the comets that orbit the Sun. Other stars within 100 light years include Barnard’s Star, Alpha Centauri, Sirius, Procyon, Tau Ceti, Epsiton Eridani, and Tau Ceti, and 93 other stars. [Universe and Beyond, pg 13, 2004] [1: Greater Distances]

3.) It took until 2002 to upgrade Hubble’s camera to get a blurry glimpse of the first galaxies. The book says that 99% of the universe is invisible (gas and dust) full of dark matter (23%) and dark energy (73%) and 3.4% of other elements. The book also says that the distance between stars is 20 times the Pluto orbit so that’s really far apart. Stars can be as close as 10 AU each other. [Universe and Beyond, pg 99, 110, 2004] This is interesting, because when I think of light years; it took 3-4 minutes for to travel to new star systems in various Star Trek episodes going five or six times light speed per second. Also Alpha Centauri seems very close at 4.4 light years when the average distance between stars is 20 light years. [Universe and Beyond, pg 74, 2004]

Scientists use the Hubble Deep Space Field to see the Andromeda Galaxy. Astronomers reduce the size of space objects to walnuts, cherries, oranges, and peas. If Earth was a dime sized and every other space object was relevant to Earth; it would take minutes to travel to new star systems, and more than a lifetime to travel to new galaxies. The reading also says that the speed of light is 674,533,030 mph and is 5,908,909,342,800 miles total in length. I can see why traveling to other solar systems take that long, because there are billions of star systems in the Milky Way Galaxy. A billion seconds is roughly 31 years, 8 months, 8 days according to my graphical calculator so I won't have seen most of the galaxy before I die even if fictionally I travel to a new star systems every few minutes. The second example I've chosen is a rotating neutron star, also known as a pulsar. Pulsars blink at you, and are easy to discover with a telescope. Stars expel gas and radiation and astronomers can tell the composition by how fast these evaporate. (Universe and Beyond, pg 16 – 18, 2004) (Gino, 2010)
I asked myself when reading the first chapter why scientists scale down the distances to fit in the palm of your hand and using atoms, peas, ping-pong balls to visualize scaled down objects seems crude and my brain refuses to melt. I also like the conversions of light-years and Astronomical Unit (AU) into more recognizable measurements such as miles. Overall, I like the technical jargon explanations over the scaled down references. However, I have found crossing star systems every couple of minutes until traveling to another galaxy in my life time impossible.
This paper explained how astronomers read the cosmos and my personal opinion on the reasons behind it.
References
Dickinson, T. (Ed.). (2004). "A Journey Through Time and Space"
The Universe and Beyond, 4th Edition. (pg 11-19) Canada: Firefly Book, Inc.
Gino, C. (2010). Week 01 - The Universe as We Know It
Retrieved April 9, 2010, from Rasmussen website
http://rasmussen.learntoday.info/section/default.asp?id=SPR10-G239-10