Astronomy

1. Describe the components of the geocentric view of the universe that was held by the early Greeks. How did Ptolemy account for the motions of the celestial bodies in his model?

The ancient Greeks believed that were circular not elliptical. In Ptolomy's interpretation of the solar system, it was assumed that the Earth was not only the center of the solar stystem but also the center of the universe. Ptolomy's model accounted for the movements of the planets by assuming that every planet moved on an epicycle that moved in a larger circle called a deferant. Stars were assumed to move outside these planetary spheres.

2. List and describe two of the minor members of the solar system.

-Pluto: is a dwarf planet, it was assigned this in 2006. It was origionally discovered in 1930 and not visable with the naked eye. It occasionally orbits Neptune, the last time this took place was from 1979-1999.

-Charon (Moon): it is a moon, discorved in 1978 and half the diameter of Pluto. It is mostly made of ice and is the largets object in the Kuiper Belt.

3. The change from ancient to modern astronomy wasn’t easy. It required considerable work and commitment by five key scientists. List and describe the contributions made to modern astronomy by Nicolaus Copernicus,Tycho Brahe, Johannes Kepler, Galileo Galilei, and Sir Isaac Newton.

Nicolause Copernicus: He formulated the Heliocentric Model that placed the Sun at the center of the Universe rather than the Earth.

Tycho Brahe: He invented the Tychonic System which combined Copernicus's Heliocentric Model and Ptolemaic System. The Sun, Moon and stars revolve around the Earth, and the other five planets revolve around the Sun.

Johannes Kepler: He is known for inventing The Laws of Planetary Motion.

-The orbit of a planet is an ellipse with the Sun as one of the two foci.

-A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.

-The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.

Galileo Galilei: called the father of observational astronomy, the father of modern physics, the father of science and the father of modern science. He supported Copernicanism and made many improvements to the telescope. He confirmed the phases of Venus, the discovery of the four largest satellites of Jupiter, observation and analysis of sunspots.

Sir Isaac Newton: He formulated the Laws of Motion and Universal Gravitation.

4. Explain what criteria determines whether a planet is to be considered either Jovian or terrestrial planets. Briefly describe each planet, incorporating the particularities of each.

In order for a planet to be considered either Jovian or terrestrial size, density, composition, and rate of rotation are taken into account. Jovian planets are larger than other planets and have many moons. Jovian planets are known as gas giants. Terrestrial planets are composed of silicate rocks and metals. They are the inner planets closest to the sun. They have a solid planetary surface.

Jupiter: Is the largest planet in the solar system and has the greatest mass. It is bright and can be viewed with the naked eye. It has 63 moons, which is more than any other planet in the solor system. Jupiter does have rings although very faint.

Saturn: Is the second largest planet in the solar system, with very distinct rings. Saturn has 61 moons.

Uranus: Is the seventh planet from the sun and the third largest in the solar system. It is known as an “ice giant” because its atmosphere is primarily hydrogen and helium.

Neptune: Is th eighth planet from the sun and is the fourth largest in the solar system. It was once visited by the Voyager 2. Neptune is very similar to Uranus. It has winds that can reach up to 2000 km/hr.

Terrestrial Planets:

Mercury:

Venus:

Earth:

Moon:

Mars:

Vesta:

Ceres:

Pallas:

5.Describe stellar parallax and explain how one would mathematically meausre and calculate the distance to a star using this method

Stellar Parallax is an interstellar scale. It measures the apparent shift of position of any nearby star against the background of distant objects. It is created by different orbital positions of the Earth, extremely small shifts are observed in time intervals of six months when the Earth arrives on the opposite side of the Sun in orbit.The baseline is two astronomical units between observations. Once a stars Stellar Parallax is known, the distance from earth can then be figured out triganometrically.

6. Discuss Earth's Moon. Elaborate on the following: Maria, Craters, regolith, highlands, and theories of the moons origin.

The moon lacks an atmosphere, so any erosion on the moon is not caused by weather. It has lower gravity and because it is small it cools quickly.

Maria: are the product of volcanic erruptions on the moon. They are large flows of basaltic lava. The oldest Maria is about 4 billion years old and the youngsest is about 3 ½ billion years old. Maria can be seen with the naked eye.

Craters: Are formed when a solid body like a comet or an astroid collide with the surface of the moon.

Regolith: are the results of many billions of years of collisions with astroids and comets. These impacts had pulverized the surface material. This is a fine grain layer called regolith. Regolith can be 2 meters thick and contain material such as rocks, bedrock, and glass particals formed during impact.

Highlands: The highlands are easy to spot, they are the contrast between the light and dark spots on the moon. The lighter surfaces are the lunar highlands.

There are five theories concerning the moons origins.

-The Fission Theory: The moon was once apart of the Earth and somehow separated from the Earth early in the history of the Solar system. The Pacific Ocean is the most popular site from where the moon originated.

-The Capture Theory: The Moon was formed somewhere else, and was later captured by gravitational forces of the earth.

-The Condensation Theory: The Moon and Earth condensed together from the original nebula that formed the Solar System.

-The Colliding Planetesimals Theory: The interaction of earth-orbiting and Sun-orbiting Planetesimals (ex. Astroids) early in the history of the Solar System led to their breakup.

-The Ejected Ring Theory: A planetesimal the size of Mars struck the earth, ejecting large volumes of matter. A disc of orbiting material was formed and this matter eventually condensed to form the Moon in orbit around the Earth.

7. Describe the major types of galaxies and provide examples of each.

Spiral Galaxies- Are shaped like pinwheels with arms spinning outward. Examples would be the Milky Way and Andromeda

Elliptical Galaxies- Are flattened spheres thinner than spiral form. They have very little interstellar activity. Example would be Maffie 1 Galaxy.

Lenticular Galaxies- Are flattened galaxies without a spiral structure. Example would be The Spindle Galaxy in Draco.

Irregular Galaxies- Don't have any shape. Examples would be Hoag's Galaxy, The Magellanic Clouds and NGC 1427A.

8. List and explain the stages of the life cycle of a star.

Stars are born from nebulae and consist of hyrdrogen and helium gas. Stars live for less than a million years before exploding as supernovae.

Nebulae: A nebulae is a cloud of gas, hyrdrogen, and dust in space.

Star: Is born from nebulae.

Red Giant: Is a large bright star. It is fromed in the later evolution of a star, like the Sun.

Red Dwarf: They are very cool faint small stars.

White Dwarf: This is a small very hot star in the last stages of a stars life.

Supernovae: This is the death of a star. This is when a star explodes.