Our Solar System Our solar system includes the sun, the planets and many other smaller objects Astronomers use astronomical units to measure distances in our solar system
Our Solar System An astronomical unit (AU) is the average distance between the Earth and the sun or 150 million kilometers
Solar System The solar system is divided into two main parts –Inner Solar System –Outer Solar System
Inner Solar System These are the four planets closest to the sun and are closely spaced together They are known as the terrestrial planets because their surfaces are dense and rocky
Outer Solar System These are the four planets furthest from the sun The outer planets are composed mostly of gases and are much bigger than the inner planets
Planets Movement Period of Revolution- Time it takes for a planet to make one revolution around the sun. This is called a year. Period of Rotation- Time it takes for a planet to make one revolution on its axis. This is called a day
NEBULA – a large cloud of gas and dust in interstellar space Two forces interacting in nebulas: 1.Gravity 2.Pressure
TEMPERATURE – is a measure of average kinetic energy of the particles in an object. If particles in a nebula have LOW kinetic energy, they move SLOWLY and the temperature of the cloud is very LOW. If particles in a nebula have HIGH kinetic energy, they move FAST and the temperature of the cloud is HIGH.
Gravity and Pressure in a Nebula 1.GRAVITY causes the particles in a nebula to be attracted to each other. 2.As particles move close together, collisions cause PRESSURE to increase and particles are pushed apart 3.If the inward force of gravity is balanced by outward pressure, the nebula becomes stable.
The balance between gravity and pressure can be upset by: –Two nebulas collide –A nearby star explodes When the balance is upset – small regions of the nebula are compressed and form GLOBULES (GAS CLOUDS)
Globules - very dense - contract under their own gravity – collapses inward Temperature increases - THE STAGE IS SET FOR STAR FORMATION SOLAR NEBULA – the cloud and dust that formed our solar system
HOW THE SOLAR SYSTEM FORMED 1.Young solar nebula BEGINS TO COLLAPSE – it took about 10 MILLION years for the solar system to form. 2.The solar nebula rotates, flattens, and becomes warmer near its center. 3.PLANETESIMALS begin to form WITHIN THE SWIRLING DISK.
A PLANETESIMAL is a small planet 4. As the largest planetesimals grow in size, their gravity attracts more gas and dust. 5.The smaller planetesimals collide with the larger ones, and planets begin to grow. 6.A star is born, and the remaining gas and dust are blown out of the new solar system.
The largest planetesimals formed near the outside of the rotating solar disk, where hydrogen and helium were located. These outer planets grew to huge sizes and became gas giants * SOL QUESTION – Jupiter’s “Great Red Spot” is a storm system more than 400 years old and about 3x the diameter of Earth The Outer Planets
Are Jupiter, Saturn, Uranus and Neptune
Closer to the center of the nebula temperatures were TOO HOT for gases to remain Therefore the inner planets are made mostly of ROCKY MATERIAL. THE INNER PLANETS
The Inner Planets Are Mercury, Venus Earth and Mars
Mercury Very similar to our moon (rocky, lots of craters) Rarely see (too close to sun) Very thin atmosphere
Venus Earth’s twin (similar diameter, mass, density) Hottest planet because of greenhouse effect Very thick clouds Active Volcanoes Retrograde Rotation (Day is longer than year) Mapped using radar
Mars Evidence of liquid water – Dust storms Tallest mountain in solar system= Olympus Mons (3x Everest) Valles Marinaris (Width of US) Polar Ice caps (CO 2 ) Fossils? 2 Moons: Phobos & Deimos
Fossils on Mars?
Olympus Mons & Valles Marineris
Ice Caps on Mars
Asteroid Belt Failed planet? All matter in asteroid belt = 1/10 of our moon Located between Mars and Jupiter 100,000 + Pebbles – 100s of Km
As the planets were forming the center of the nebula became very dense and hot that hydrogen atoms began to fuse to form HELIUM. Fusion creates large amounts of energy and created enough outward pressure to balance the inward pull of gravity. The gas stopped collapsing and OUR SUN was born! BIRTH OF A STAR
Formation of the Sun
Solar Facts Mass: 330,000 x Earth Diameter: 1.4 million Km Temperature Range: 4,000 C (Sunspots) to 14,000,000 C (Core) Rotational Rate: days Age: 4.5 Billion Years Life Expectancy: 5 Billion years (more) Distance to Earth: 150,000,000 Km Distance to nearest star: 4.3 Light Years
PARTS OF THE SUN 1.CORE – center – where the sun’s energy is produced 2.RADIATIVE ZONE – very dense region about 300,000 km. thick
PARTS OF THE SUN 3.CONVECTIVE ZONE – about 200,000 km. thick – where gases circulate 4.PHOTOSPHERE – visible part that can be seen from Earth
PARTS OF THE SUN 5.CHROMOSPHERE – thin region below the corona, only about 30,000 km. thick 6. CORONA – forms the sun’s outer atmosphere
Albert Einstein showed that matter and energy are interchangeable E=mc 2 E=energy, M=mass, c=speed of light Since c is such a large number, tiny amounts of matter can produce a huge amount of energy NUCLEAR FUSION – two or more low mass nuclei fuse to form another nucleus.
Nuclear Fusion H + H + H + H = He + Energy 1 Helium atom is lighter than the 4 Hydrogen atoms, lost mass becomes energy How energy is produced in the center of stars Takes millions of years for energy to reach the sun’s surface. It takes 8.3 minutes for sunlight to reach the Earth
FOUND ON THE SUN The circulation of the convective zone and photosphere combines with the sun’s rotation create MAGNETIC FIELDS that reach far out into space. SUNSPOTS are created when the sun’s magnetic fields slow down activity in the convective zone resulting in cooler areas of the photosphere. A SUNSPOT is a dark are of the photosphere that is cooler than the surrounding areas and has a strong magnetic field
Map of Sunspots
SUNSPOTS Sunspots vary in shape and size The numbers and locations of sunspots change every 11 years – affect climate
Magnetic field that cause sunspots, also cause SOLAR FLARES. SOLAR FLARES are regions of extremely high temperature and brightness that develop on the sun’s surface
Solar flares sends huge streams of electrically charges particles into the solar system.
Solar flares are usually associated with sunspots and can interrupt radio communications.