Post on 26-Dec-2015
transcript
• 186,000 miles a second• 300,000,000 meters per
second • 700 million miles an hour.
• For scale, the distance from the Earth to the Moon is about 239,000 miles.
• The distance light can travel in a year is called a "light year." The light year is one of the basic measures of distance for astronomy.
SPEED OF LIGHT
• NOTHING TRAVELS FASTER THAN THE SPEED OF LIGHT.
Distance
• Earth is 93million miles from Sun (150million km)– 1 AU (astronomical unit)
http://www.northern-stars.com/solar_system_distance_scal.htm
Because space is so vast, astronomers have a created different unit for measuring the distances in space known as an astronomical unit.This is the distance from the Sun to the Earth.
AU’s
• Mercury .38• Venus- .72• Earth- 1.0Earth- 1.0• Mars- 1.5• Jupiter- 5.2• Saturn- 9.5• Uranus- 19.2• Neptune- 30.0 • Pluto- 39.4
• Scale solar system
• 1AU= 1m(earth 1m away from sun)
General Characteristics of the Solar System
Planetary orbits and rotation• planet and satellite orbits are in a common plane• nearly all planet and satellite orbital and rotation
motions are in the same direction
What is a planet?
• The definition of planet set in 2006 by the International Astronomical Union (IAU) states that in the Solar System a planet is a celestial body that:– is in orbit around the Sun,– has sufficient mass to assume
hydrostatic equilibrium (a nearly round shape), and
– has "cleared the neighborhood" around its orbit.
Nearly all planet and satellite orbital and rotation motions are in the same direction
General Characteristics of the Solar System– Terrestrial planets- small, composed of rock and metallic elements (metals)
– Jovian planets-large, composed of gases and frozen compounds
4 Terrestrial PlanetsThe Inner Planets
• Mercury, Venus, Earth, Mars• Rocky and metallic• Small• No rings Very few moons
MERCURY
• closest to our Sun• small, rocky planet
- much like our Moon
• It is covered with craters and has changed very little from when it was first formed
One side HOT: 800o FOther side COLD: -275o C
Mercury Facts
•Average Distance From Sun – Kilometers: 57,000,000 – Miles: 36,000,000
•Astronomical Units: 0.387 •Length of Day: 58 days 15 hours 30 minutes •Length of Year: 87.97 days
– Average Orbital Speed – Kilometers/Second: 47.89 – Miles/Second: 29.76
•Number of Known Satellites: 0
VENUS• Intense heat and
volcanic activity. • Similar in structure and
size to Earth• Venus' thick, toxic
atmosphere traps heat in a runaway "greenhouse effect."
VENUS
• Average Distance From Sun Kilometers: 108,200,000 Miles: 67,000,000
• Astronomical Units: 0.723
• Length of Year: 224.7 days
• Length of Day: 243 days
• Number of Known Satellites: 0
• Only planet known to have
life• Only planet not named after a Greek/Roman god
EARTH
Earth• Average Distance From Sun • Kilometers: 149,600,000 • Miles: 93,000,000 • Astronomical Units: 1.000 • Length of Year: 365.26 days • Length of Day: 23 hours 56
minutes 4 seconds • Volume (Earth=1): 1.000 • Number of Known Satellites: 1
The Asteroid Belt• Separates Inner and Outer planets• Asteroids left-overs from the formation of the Solar System.
While some have suggested that they are the remains of a proto-planet that was destroyed in a massive collision long ago, the prevailing view is that asteroids are leftover rocky
matter that never successfully coalesced into a planet.
4 Jovian PlanetsThe Outer Planets
• Jupiter, Saturn, Uranus, Neptune• Gases & frozen gases• Very large• All have rings• Many moons
Jupiter• 5th planet (1st outer planet)• 9.84 hours to rotate• 4,333 days to revolve
– (12 earth years)
• 66 moons• 4 Rings• Largest PlanetAtmosphere - Hydrogen, Helium, Oxygen, Nitrogen
and Methane
Saturn
• 6th planet• 10.2 hours to rotate• 10, 759 days to revolve (29 earth years)• 62 moons• 23 Rings• Atmosphere Hydrogen and Helium
Uranus
• 7th planet• 17.9 hours to rotate• 30,688 days to revolve
– (84 earth years)
• 27 moons• 13 Rings • Atmosphere: Methane, Hydrogen and Helium• Tilted on its side
Neptune
• 8th planet• 19 hours to rotate• 60,181 days to revolve
(164.8 earth years)• 13 moons• 9 Rings• Methane atmosphere gives it bluish color
Is Pluto a Planet?• Dwarf planet• From its time of discovery in 1930 to 2006 it was considered to be the ninth
planet in the solar system, but because additional objects have been discovered including Eris which is 27% more massive, the IAU reclassified Pluto and the other objects as dwarf planets. The New Horizons spacecraft was launched on January 16, 2006 and will make its closest approach to Pluto on July 14, 2015. This mission will provide an increased amount of information about this peculiar dwarf planet.
• Unlike planets, dwarf planets lack the gravitational muscle to sweep up or scatter objects near their orbits. They end up orbiting the sun in zones of similar objects such as the asteroid and Kuiper belts.
How far is the Moon from Earth?
The moon is 30 Earth’s away
COMETS
A comet is an icy ball that releases gas or dust. They are often compared to dirty snowballs.
COMETS
• Halley's Comet
ASTEROIDS
• Asteroids are rocky, airless worlds that orbit our sun• too small to be called planets • Tens of thousands of these "minor planets" are
gathered in the main asteroid belt, a vast doughnut-shaped ring between the orbits of Mars and Jupiter.
• Asteroids that pass close to Earth are called Near-Earth Objects (NEOs).
METEORIODS
• Little chunks of rock and debris in space are called meteoroids.
• They become meteors -- or shooting stars -- when they fall through a planet's atmosphere
• Pieces that survive the journey and hit the ground are called meteorites.
KUIPIER BELT and OORT CLOUD• The Kuiper Belt is a disc-
shaped region of icy objects beyond the orbit of Neptune -- billions of kilometers from our sun.
• Oort cloud is a sphere of ice dwarfs and ice particles that surround our solar system.
Pluto and Eris are the best known of these icy worlds. There may be hundreds more of these ice dwarfs out there. The Kuiper Belt and even more distant Oort Cloud are believed to be the home of comets that orbit our sun.
General Characteristics of the Solar System
Planetary orbits and rotation• planet and satellite orbits are in a common plane• nearly all planet and satellite orbital and rotation
motions are in the same direction
How do we classify stars?
A.Size
B.Temperature and Color
C.Brightness
Temperature and color• The color of the star is dependent on the temp of the star.• Red – coolest stars• Blue – hottest stars
• Order from coolest to hottest• Red, red-orange, yellow, white, blue 3000K 6000K 30,000K
Stars have Different colors which indicate different temperatures
Temperature and Color
SizeGiants/supergiants- large and very large stars. Many of these are very far awayWhite dwarfs- very small stars – about the size of the EarthNeutron stars- even smaller stars – only 20 km in diameter.
Medium sized stars- many stars this size. The size of our Sun.
Binary star systems contain two stars that orbit around their common center
of mass. Many of the stars in our galaxy are part of a binary system.
Binary Stars are used to
determine the mass of the star.
How do we measure stars?
Parallax- the apparent change in position of an object when you look at it from different places.
Parallax
The closer the star is to Earth, the larger the shift will be
Parallax
Only good for measuring stars close to us. Not farther than 1000 light years away. Why?
The movement would be too small to measure accurately.