Chapter 11

11.2 The Sun and the Planetary System Our solar system is full of planets, moon, asteroids, and comets, all in motion around the Sun. Most of these components are separated by great distances. Each planet has its own distinct characteristics. Comets, icy debris, and dwarf planets travel at the outermost reaches of our solar system.

Formation of the Solar System Our solar system was formed more than 4.5 billion years ago. As the Sun burst into existence, the leftover material combined to form eight planets and numerous other planetary bodies: moons, asteroids, and comets. Closest to the Sun are the inner planets (terrestrial planets) and further away are the outer planets (gaseous giants). Our solar system was formed more than 4.5 billion years ago. As the Sun burst into existence, the leftover material combined to form eight planets and numerous other planetary bodies: moons, asteroids, and comets. Closest to the Sun are the inner planets (terrestrial planets) and further away are the outer planets (gaseous giants).

The SUN The sun contains more than 99% of all the solar systems mass. The composition of our star is mainly hydrogen gas, the most common element in space. The hydrogen in the sun fuses with helium and radiates this energy outward. The sun contains more than 99% of all the solar systems mass. The composition of our star is mainly hydrogen gas, the most common element in space. The hydrogen in the sun fuses with helium and radiates this energy outward.

The SUN The sun is a complex system of bubbling gases that occasionally send out spectacular explosions and violent solar flares. It has no solid surface but many distinct features. The sun is a complex system of bubbling gases that occasionally send out spectacular explosions and violent solar flares. It has no solid surface but many distinct features.

Solar Winds Energetic gases in the corona are ejected in a sudden burst. When these high energy particles rush past the Earth they create “solar winds.” These winds are deflected by the magnetic field around the earth’s poles. This is what causes our Northern Light shows. Sometimes these winds can disrupt satellites and temporarily knock out power supplies to Earth. Energetic gases in the corona are ejected in a sudden burst. When these high energy particles rush past the Earth they create “solar winds.” These winds are deflected by the magnetic field around the earth’s poles. This is what causes our Northern Light shows. Sometimes these winds can disrupt satellites and temporarily knock out power supplies to Earth.

The PLANETS To be considered a planet the body must orbit one or more stars, be large enough that its own gravity holds it in a spherical shape, and be the only body occupying the orbital path.

MERCURY o closest planet to the Sun o smallest, slightly larger than our moon than our moon o no significant atmosphere o extreme temperatures 400 o C to -183 o C 400 o C to -183 o C o changes in temperatures cause contraction and cause contraction and expansion of crust forming expansion of crust forming many craters and cracks many craters and cracks

VENUS o closest to Earth o similar in composition to Earth o atmosphere is almost all carbon dioxide o thick clouds of sulphur dioxide cover the planet o planet has volcanoes, lava flows, cracks and rifts

EARTH o blue planet, 3 rd rock from the Sun o suitable atmosphere and temperatures o water found in all 3 states (solid, liquid, gas) o water covers nearly 3/4 of the entire planet o atmosphere is almost completely N 2 and O 2

MARS o “Red Planet” because of the iron content in soil o half the size of Earth but same surface area o has a volcano 3x the height of Mt Everest o has 8 km deep canyon that stretches from Vancouver to Toronto o thin atmosphere of carbon dioxide o has winds up to 900km/hr o dust storms and two polar ice caps

JUPITER o largest planet in solar system o gas giant o mass 2.5 times greater than all planets combined o great “Red Spot” (visible from Earth) is a storm raging in clouds of hydrogen and helium that forms the outer layers o has the shortest day of any planet, turning once on it’s axis every 10 hrs

SATURN o gas giant identified by the elaborate system of rings formed from ice particles o ice rings are 250,000 km wide and as thin as 10m o planet is composed mainly of hydrogen and helium

URANUS o fourth most massive planet, another gas giant o Similar composition to Jupiter and Saturn o Also has a system of rings made of ice and dust o Blue colour is from the methane gas in its atmosphere (methane absorbs red light) o it orbits differently than other planets because its axis is tilted

NEPTUNE o outermost planet and 3 rd most massive o dark blue colour due to methane similar to Uranus o also has a ring system but is faint o when voyager 2 flew past the planet it noticed a spot similar to Jupiter, which is likely a storm cloud o Hubble telescope has discovered another storm cloud near the northern hemisphere

The MOON All planets except Mercury and Venus have one or more orbiting companions. Over 150 moons have been discovered orbiting planets in our solar system. Astronomers call these orbiting companions “satellites.” All planets except Mercury and Venus have one or more orbiting companions. Over 150 moons have been discovered orbiting planets in our solar system. Astronomers call these orbiting companions “satellites.”

ASTEROIDS  Asteroids are small bodies that are leftover remains of the formation of the solar system.  Most asteroids orbit the sun in a band between Mars and Jupiter. They range in size from grains of sand to 1,000 km wide like “CERES.”

COMETS Comets are often referred to as “dirty snowballs.” Comets are often referred to as “dirty snowballs.” They are composed of ice, rock, and gas. Space probes have found that there is more rock than once thought. They originate from the Kuiper Belt and the Oort Cloud. Once they get close enough to the sun we can see the trail of gas, ice and dust streaming behind. They are composed of ice, rock, and gas. Space probes have found that there is more rock than once thought. They originate from the Kuiper Belt and the Oort Cloud. Once they get close enough to the sun we can see the trail of gas, ice and dust streaming behind.

Trans-Neptunian Objects  Anything that orbits the sun past Neptune are considered Trans- Neptunian objects. Scientists believe there are about 23 objects orbiting in the Kuiper belt.  Some of these objects or dwarf planets are:  Pluto  Ersis in the Kuiper belt

Oort Cloud At the farthest reaches of the Suns gravitational influence is a spherical cloud of small icy fragments of debris called the Oort Cloud. It is another source of comets. It is approximately 1/4 the distance to the next closest star. At the farthest reaches of the Suns gravitational influence is a spherical cloud of small icy fragments of debris called the Oort Cloud. It is another source of comets. It is approximately 1/4 the distance to the next closest star. Section 11.2 Quiz

11.3 Measuring Distances in Space Astronomical units are used to measure distances within the solar system. Light years are used to measure distances to other bodies far beyond our solar system. Distances measured from Earth to some bodies can be determined by using triangulation and parallax. Astronomical units are used to measure distances within the solar system. Light years are used to measure distances to other bodies far beyond our solar system. Distances measured from Earth to some bodies can be determined by using triangulation and parallax.

How BIG is SPACE? Section 11.3 Quiz