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Gravity and Space

Gravity and Space. Gravity . Comes from mass We don’t feel the force of gravity b/n objects on Earth because nothing on Earth is more massive than the Earth. Lies along a line connecting the centers of the 2 objects. Gravity .

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Gravity and Space

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  1. Gravity and Space

  2. Gravity • Comes from mass • We don’t feel the force of gravity b/n objects on Earth because nothing on Earth is more massive than the Earth. • Lies along a line connecting the centers of the 2 objects

  3. Gravity • Newton’s Law of Universal Gravitation – A mathematical rule that tells us how the strength of the force of gravity depends on the mass and distance. • The greater the mass, the greater the force of gravity. • The closer the two masses are, the greater the force of gravity.

  4. Orbital Motion • Orbit – The repeating circular (or elliptical) path an object takes around a gravity source, such as a planet or star. • Why doesn’t the Moon crash into the Earth?

  5. Earth and Sun • Which is more massive? Earth or the Sun • Force of gravity from the Earth affects a person more than the force of gravity from the Sun. Therefore, we stay on the planet, and are not drifting toward the Sun.

  6. The Earth and Moon • The moon is 81x smaller than the Earth • Gravitational Locking – Earth’s gravity has locked the moon’s rotation to its orbit around Earth. • Lunar day = 27.3 Earth days • Same side of the moon is always facing toward the Earth.

  7. Phases of the Moon • What are the phases of the moon? • Waxing – Moon appears to be getting larger – heading toward the full moon • Waning – Moon appears to be getting smaller – heading toward the new moon

  8. Tides • Moonward force = 0.00003N • Although most objects don’t “feel” this force, water is affected. • Tide – A cycle of rising and falling sea levels that repeats every 12 hours. • One tide is caused by the oceans’ attraction to the Moon. The other is caused by the ocean being “flung” outward. • http://www.youtube.com/watch?v=CTQ6ciHENgI

  9. Planets • Planets – massive round body held together by its own gravity that revolves around a star in its own orbit. • 8 major planets in our solar system • Do not emit their own light. • Some are categorized as terrestrial • Some are categorized as gas planets

  10. Solar System • Solar system – the Sun, planets, moons, and other objects that are gravitationally bound to the Sun. • Divided into inner and outer planets, by the asteroid belt • Sun the largest object

  11. Solar System • Solar system measured in astronomical units (AU) • Astronomical unit – A distance equal to 150 million km (149,600,000km) or the distance from Earth to the Sun. (92,960,000 miles)

  12. Other objects in the solar system • Asteroid – orbits the Sun, but is too small to be considered a planet. • Comet – object in space made mostly of ice and dust. • Meteor – A chunk of burning rock traveling through Earth’s atmosphere • Meteorite – A meteor that has travelled through Earth’s atmosphere and strikes the ground.

  13. The Sun and Stars • Star • Hot ball of gas • Extremely massive • Energy produced through nuclear fusion (the reason stars emit light) • Nuclear fusion – Reactions which combine light elements such as H into heavier elements, such as He, releasing large amounts of energy.

  14. Stars • Fusion occurs in the core of the star. • Core is extremely dense. (158.0 g/cm3)

  15. Sun • A yellow star, that is the center of our solar system • Corona • Photosphere • Chromosphere • Convection zone • Radiaton zone • Core • Sunspots

  16. Classification of Stars • Size, temperature, color, and brightness • Giant stars • 2 types: • Blue giants – hot and more massive than the Sun • Red giants – similar mass to the Sun, much cooler. Began as sun-like stars, but cooled as they expand

  17. Classification of Stars • Smaller stars • 2 main types • Dwarf • About the size of smaller planets • Neutron stars • 20-30km in diameter, about the size of a big city

  18. Classification of Stars • Color of light is related to a star’s energy (temp) • Red = lowest energy • Yellow, Green, & Orange = medium energy • White = mixture of all colors at equal brightness • Blue & Violet = most energy

  19. Galaxies • Galaxy a huge group of stars, dust, gas, and other objects held together by gravitational forces. • Types: Elliptical, spiral, lenticular • MilkyWay galaxy • Spiral galaxy • 100,000 ly across and 3,000 ly thick • Sun is 26,000 ly from the center

  20. Galaxies • Distances between galaxies are a million times greater than the distances between stars. • Use luminosity to find distance of nearer galaxies. • >150 million ly scientists compare size and type with closer galaxies to estimate the luminosity of farther galaxies.

  21. Light Years • A light year is the distance light travels in one year through space. • Speed of light (c) = 300,000 km/sec • 1 ly = speed of light X time

  22. Light years • Nearest star is 4.3 light years • Nearest galaxy is 25 million light years (Canis Major dwarf galaxy) • Megaparsec = 3.08567758x1019km

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