AST101H1 Lecture Notes - Lecture 2: Hubble Space Telescope, Galactic Center, Local Group

Which, if any, of the following statements is/are true?

1)Our galaxy, The Milky Way, is a member of The Local Group, whichis one of several groups of galaxies located in the VirgoSupercluster.
2)Most astrophysicists believe that our Solar System formed from animmense cloud of gas and dust about 4-1/2 million years ago.
3)Planets are believed to have formed by a process known asaccretion.
4)Two key elements in the Condensation Theory of PlanetaryFormation are 5)Conservation of Angular Momentum and CondensationNuclei.
6)The name of the second largest object in the Universe is TheSouthern Wall.
7)In our Solar System, the four jovian planets, Jupiter, Saturn,Uranus, and Neptune, are separated from the four terrestrialplanets, Mercury, Venus, Earth, and Mars, by the Kuiper Belt.
8)Our star, The Sun, is located on the Orion Arm, about 26,000light-years from the center of the Andromeda Galaxy.
9)It takes a photon of light about 4-1/5 years to travel from ourSolar System to the second closest star to Earth, ProximaCentauri.
10)The full range of human knowledge about our Universe spans about40 or 41 orders of magnitude on a spatial scale and about 13.7billion years on a temporal scale.
11)It takes a photon of light about 5-1/2 hours to travel from theSun to the orbit of the former planet Pluto.

Alpha Centauri, the nearest star to our solar system, is 4.3 lightyears away. Assume that Alpha Centauri has a planet with anadvanced civilization. Professor Dhg, at the planet's AstronomicalInstitute, wants to build a telescope with which he can find out ifthere are planets orbiting the sun.
What is the minimum diameter for an objective lens that will justbarely resolve Jupiter and the sun? The radius of Jupiter's orbitis 780 million {\rm km}. Assume lambda =600\;{\rm nm} .

The great astronomer Edwin Hubble discovered that all distant galaxies are receding from our Milky Way Galaxy with velocities proportional to their distances. It appears to an observer on the Earth that we are at the center of an expanding universe. Figure 3.64 illustrates this for five galaxies lying along a straight line, with the Milky Way Galaxy at the center. Using the data from the figure, calculate the velocities: (a) relative to galaxy 2 and (b) relative to galaxy 5. The results mean that observers on all galaxies will see themselves at the center of the expanding universe, and they would likely be aware of relative velocities, concluding that it is not possible to locate the center of expansion with the given information.

Figure 3.64 Five galaxies on a straight line, showing their distances and velocities relative to the Milky Way (MW) Galaxy. The distances are in millions of light-years (Mly), where a light-year is the distance light travels in one year. The velocities are nearly proportional to the distances. The sizes of the galaxies are greatly exaggerated; an average galaxy is about 0.1 MlY across.