Astronomy 3L Vocabulary/Review for Quiz #2 the Quiz Will Be on Our

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Astronomy 3L Vocabulary/Review for Quiz #2 The quiz will be on our gravity and limiting magnitude activities. From the Mass of the Earth activity, you will want to be familiar with the quantities that control the strength of the gravitational force between two objects, and how the gravitational force can be used to measure the mass of the Earth (you will not be tested on your math skills, but on your conceptual grasp of gravity). You should be familiar with the concept of limiting magnitude, and understand the process we used in class to measure limiting magnitude under different conditions. You should also know what sorts of observing conditions can change the limiting magnitude observed in the night sky. Absolute Magnitude – The theoretical apparent magnitude that a star would have if it were located exactly 32.6 light years (10 parsecs) away from Earth. For example, the Sun’s apparent magnitude is about -27, while its absolute magnitude +4.8. Apparent Magnitude – The magnitude of a star as it appears in the night sky. Objects visible to the naked eye have apparent magnitudes of +6.0 or lower. For example, the brightest star visible (Sirius) has an apparent magnitude of -1.44, and the apparent magnitude of the full moon is about -13. Gravitational Force – The force that attracts any two objects with mass towards each other. The strength of the force increases with the mass of either of the two objects, and increases as the distance between the objects shrinks. Limiting Magnitude – The magnitude of the faintest object that can be seen (either with the naked eye or a particular instrument) in the night sky, given environmental observing conditions such as weather, Moon phase, and light pollution. Magnitude – In astronomy, a measure of the comparative brightness or intensity of a star. Magnitude is expressed on an exponential scale, where the brighter objects have a lower (or very negative) magnitude. Magnitudes can be apparent (see Apparent Magnitude) or absolute (see Absolute Magnitude). Mass – The amount of matter contained in a given object Seeing – The technical term that describes the amount of blurring and twinkling of light coming from distant objects due to Earth’s atmosphere. The seeing gives an idea of how sharp stars will look through a given telescope or with the naked eye. Weight – A measurement of the strength of the gravitational force between a person and the planet they are standing on (typically, Earth). .

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