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A planet is an object orbiting a star or stellar remnant that is large enough to be rounded by its own gravity. However, it is not large enough to cause thermonuclear fusion and has cleared its neighbouring region of planetesimals. Planets are divided into two main categories, low-density gas giants, and smaller rocky terrestrials.

In the Earth’s solar system there are eight planets. The four terrestrials are located closest to the sun. The four gas giants are the furthest from the sun. The eight planets in the solar system in order from increasing distance from the sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Six of the eight planets are orbited by one or more natural satellites. There are also five recognized dwarf planets in the Solar System, Ceres, Pluto, Haumea, Makemake and Eris.

Since 1992, hundreds of other planets orbiting around stars in the Milky Way have been discovered. These planets range in size and characteristics from the terrestrial planets similar to Earth and the gas giants larger than Jupiter.

Each planet has its own physical characteristics. They will each have a unique mass, internal differentiation, atmosphere and magnetosphere. This is precisely why life cannot be sustained on every planet. However, exploring other planets allows scientists to see clues on how the universe was created.

Discussing Astronomy in regards to Philosophy

How can we talk about the evolution of stars over billions of years when human beings have been observing stars for only a few thousand years? Some advances in our knowledge have been made possible through better equipment, such as Hubble's discoveries using the 100-inch Hooker telescope at Mount Wilson. What other major disc

Life on Mars

Please help answer the following questions regarding whether life ever existed on Mars. Include references. Do we know whether Mars ever had life at any time during its past? What argues in favor of the position that it may once have harbored life?

Normal and Active Galaxies

Over 200 word response with reference that compares normal and active galaxies. Please help with the following problem. Name two basic differences between normal and active galaxies. How do astronomers account for the differences in the spectra observed from active galaxies?

Testing the Theory of General Relativity

Please provide an over 200 word response with reference that describes how to test the theory of general relativity. Why is it so difficult to test the predictions of the theory of general relativity? Describe two tests of the theory.

Sidereal and Solar Days - Earths rotation

Please help with the following problem: Contrast the sidereal and solar days. How, and by roughly how much, would the length of the solar day change if Earth's rotation were suddenly to reverse direction?

Determination of the mass of a planet from orbital dynamics

A satellite of mass 830 kg orbits a planet of unknown mass at a distance of 29100 km from the planet's center. The orbital velocity of the satellite is 14200 m/s. * What is the mass of the planet? * How much would potential energy (PE) and kinetic energy (KE) of this satellite change as the satellite moved from a circular

Potential Resources about an alien world

The Scenario: You are a team of official investigators, sent by Earth authorities to research the possibility of establishing diplomatic relations with a newly discovered world. Your job is to investigate the planet and produce a report summarizing your findings and suggesting means for establishing relations. Three question

Tidal effects and Formation of the moon.

How does the Moon cause the Earth's tides. What are the two types of tides and why do they occur? What are the different theories proposed for the formation of the Moon. What is the most widely accepted theory? Thanks.

Geometrical calculation of planet orbit distances

I could use some help with Algebra Radicals. Thanks! Radicals Application Practice Answer the following questions. Use Equation Editor to write mathematical expressions and equations. First, save this file to your hard drive by selecting Save As from the File menu. Click the white space below each question to maintain

Collisions of planets and comets, redshift of galaxies

1. A planet orbiting a star is occasionally hit by comets. Each comet has a mass of 4.8 * 10^6 kg of which 30% is rock and 70% is water ice. Each time a comet hits the planet 40% of the mass of the comet is vaporized and the rest is added to the planet, increasing the mass of the planet. If 6 comets hit the planet every 10 years

Planetary motions overview

Please help with the following problem. Every night, all stars and planets rise in the _______ and set in the ________. What direction do the planets normally move in across the sky with respect to the background stars (prograde motion)? What is retrograde motion, and why do we see it?

Discussion on formation of rocky and gaseous planets

Discuss why the inner planets are rocky, and the outer planets are gaseous. If the Sun was substantially hotter than it is today would the range of gaseous planets in general be positioned further away from the sun then they are today? Discuss why or why not? Why is Pluto no longer considered a Planet? Any assistance with que

Newton's Law of Motions: Sample Questions

The following questions and problems are from "Physics 7th edition by Cutnell and Johnson, Chapter 4" which includes the concepts like Newton's laws of motion, the vector nature of Newton's second law of motion, type of forces (gravitational, normal, static and kinetic/frictional forces, tension force), equilibrium and non-equil

Observed emission actually left the Beta Pictoris system

(a) This question considers exoplanets, the environments in which they are born, and their methods of detection. (i) In Book 8 you were introduced to the discovery of the circumstellar disk around the star known as Beta Pictoris. With the knowledge that this object is 19.4 parsec away and using the fact that light travels at

Energy Calculations

The website in the problem isn't the greatest. Please feel free to use another source; just make sure you provide a address. Show all work step by step and provide justification and references. 1. McNary Dam a. How tall is McNary Dam? Solution: 183ft Source:

20 Mulitiple Choice Questions on Physics: Energy and Environment

1) A total of 4900 J is expended in lifting a 50-kg mass. The mass is raised to a height of a) 10 m. b) 98 m. c) 960 m. d) 245, 000 m. 2) In a good wind, a modern large wind turbine might have a power output of a) 2 kW. b) 20 kW. c)200 kW. d)2000 kW. 3) It seems possible that a serious effort to improve the effici

Astronomy of Different Atmospheres

1. Do you believe that Mars might have harbored life in the past? 2. In your opinion, is life on Earth unique? 3. Do you believe that other stars have planets with atmospheres that are similar to Earth's? 4. What do you believe is intelligence? 5. Do you think humans will ever participate in interstellar flight?

Radio signals toward Earth

Imagine that a civilization in another planetary system is sending a radio signal toward Earth. As our planet moves in its orbit around the Sun, the wavelength of the signal we receive will change due to the Doppler effect. This give SETI scientists a way to distinguish stray signals of terrestrial origin (which will not show

Two Astronomy Questions

Two Astronomy Questions, site reference if used, no minimum or max word count just enough to justify the answer. 1) Do you think it is likely that the human race will continue to exist until the Sun begins to expand into a red giant? Explain why or why not. 2) Provide an example of popular culture's use of the term black

Temperature and Heat Discussion

Physics - Fluids Description Read through chapter 11. These points will count toward your homework grade. 1. Question Details Notes Question: CJ7 11.CQ.004. Question part Submissions 1 2 3 4 0/2 0/2 0/2 0/2 As you climb a mountain, your ears "pop" because of the changes in atmospheric pressure. (

GMOs, Sustainability and the future

Should we continue to develop genetically modified foods and expand their use? Is there hope for a sustainable future, in which both environmental quality and human well-being are improved? What can we do to advance sustainability?

Physics Flat Plane Incline

1) A 5 kg block rests on a flat plane inclined at an angle of 300 to the horizon as shown in the diagram below. What would be the acceleration of the block down the plane assuming the force of friction is negligible? mgsinQ = ma 2) A projectile launched from the ground landed a horizontal distance of 120.0 m from its launch

Search for Extraterrestrial Life

Please comment on the following statement. No personal opinions please - search the web for suitable articles and comment on them. Please list the websites you use. Is it a waste of time and resources to listen for signals from intelligent life in the Universe?