The Solar System

The Sun

Mythology People have worshiped the sun and gods related to the sun for all of recorded history. People have worshiped the sun and gods related to the sun for all of recorded history. Egypt—sun god = Ra. He was considered the creator of all things. Egypt—sun god = Ra. He was considered the creator of all things. Greek—Helios. He drove the sun across the sky from east to west in his chariot. Greek—Helios. He drove the sun across the sky from east to west in his chariot.

Size of the Sun The Sun's diameter is 864,938 miles (1,391,980 km). This is almost 10 times larger than the planet Jupiter and about 109 times as big as the Earth. The Sun's diameter is 864,938 miles (1,391,980 km). This is almost 10 times larger than the planet Jupiter and about 109 times as big as the Earth. The volume of the Sun is 1,299,400 times bigger than the volume of the Earth. The volume of the Sun is 1,299,400 times bigger than the volume of the Earth. About 1,300,000 Earths could fit inside the Sun About 1,300,000 Earths could fit inside the Sun

Mass of the Sun mass of the sun = × kilograms mass of the sun = × kilograms This number was derived by using Newton’s laws of motion relating mass, velocity, gravity, and distance. This number was derived by using Newton’s laws of motion relating mass, velocity, gravity, and distance.

Rotation of the Sun The Sun has a north and south pole, just as the Earth does, and rotates on its axis. The Sun has a north and south pole, just as the Earth does, and rotates on its axis. Unlike Earth which rotates at all latitudes every 24 hours, the Sun rotates every 25 days at the equator and takes progressively longer to rotate at higher latitudes, up to 35 days at the poles. Unlike Earth which rotates at all latitudes every 24 hours, the Sun rotates every 25 days at the equator and takes progressively longer to rotate at higher latitudes, up to 35 days at the poles. This is known as differential rotation This is known as differential rotation

Composition of the Sun 71% Hydrogen 71% Hydrogen 27.1% Helium 27.1% Helium.97% Oxygen.97% Oxygen.4% Carbon.4% Carbon.09% Nitrogen.09% Nitrogen

Parts of the Sun The Corona The Corona The outer most part of the sun’s atmosphere. The outer most part of the sun’s atmosphere. Lowest levels of the corona’s temperature is 2,000,000 K Lowest levels of the corona’s temperature is 2,000,000 K Has less than 1 billionth the density of the Earth’s atmosphere. Has less than 1 billionth the density of the Earth’s atmosphere. Very irregular in form. Very irregular in form.

Solar Activity Sunspots—Occur near areas of very strong magnetic fields. Sunspots—Occur near areas of very strong magnetic fields. Magnetic fields are able to retain matter that holds an electric charge Magnetic fields are able to retain matter that holds an electric charge The strong magnetic fields in sunspots keep energy from reaching the surface of the sun. The strong magnetic fields in sunspots keep energy from reaching the surface of the sun. Sunspots are, therefore, cooler than the rest of the sun. Sunspots are, therefore, cooler than the rest of the sun.

Sun Spots Occur in an 11 year cycle. Occur in an 11 year cycle. Each 11 years the north magnetic pole and the south magnetic pole switch. Each 11 years the north magnetic pole and the south magnetic pole switch.

Flares High energy solar storms on the Sun. High energy solar storms on the Sun. No theory is widely accepted, but scientists believe that they are related to the large amounts of energy “stored” by sunspots. No theory is widely accepted, but scientists believe that they are related to the large amounts of energy “stored” by sunspots.

The Sun Song

The Planets The nine Planets The nine Planets The nine Planets The nine Planets

Mercury

Mythology In Roman mythology Mercury is the god of commerce, travel and thievery, the Roman counterpart of the Greek god Hermes, the messenger of the Gods. The planet probably received this name because it moves so quickly across the sky.

Size of Mercury Mercury’s diameter is 4,880 km Mercury’s mass is 3.30x10 23 kg

Distance to the Sun Mercury's orbit is highly eccentric; at perihelion it is only 46 million km from the Sun but at aphelion it is 70 million. Mercury's orbit is highly eccentric; at perihelion it is only 46 million km from the Sun but at aphelion it is 70 million.

Composition of Planet Mercury is a very dense planet. Mercury is a very dense planet. Scientists believe Mercury has a crust of light silicate rocks (rocks that contain Silicon and Oxygen) Scientists believe Mercury has a crust of light silicate rocks (rocks that contain Silicon and Oxygen) Mercury contains a large iron core. Mercury contains a large iron core.

Temperature of Mercury Daytime temperature may reach 750 degrees Fahrenheit Daytime temperature may reach 750 degrees Fahrenheit Nighttime temperature may reach -240 degrees Fahrenheit Nighttime temperature may reach -240 degrees Fahrenheit

Mercury’s Geology Mercury is a geologically dead planet. Mercury is a geologically dead planet. It has no plate tectonics like Earth. It has no plate tectonics like Earth. Much of the activity that takes place or has taken place on mercury is form cooling and impacting comets or meteors. Much of the activity that takes place or has taken place on mercury is form cooling and impacting comets or meteors.

Moons Of Mercury Mercury has no known moons. Mercury has no known moons. Transient of mercury— Picture of mercury as it crosses the sun. Transient of mercury— Picture of mercury as it crosses the sun.

Venus

Mythology Venus (Greek: Aphrodite; Babylonian: Ishtar) is the goddess of love and beauty. The planet is so named probably because it is the brightest of the planets known to the ancients.

Size of Venus Venus is the second planet from the Sun and the sixth largest. orbit: 108,200,000 km (0.72 AU) diameter of Venus: 12,103.6 km mass: 4.869e24 kg

Distance to the Sun Venus is on average 108 million km, or AU, to the sun. Venus is on average 108 million km, or AU, to the sun. Venus' orbit is the most nearly circular of any planet, with an eccentricity of less than 1%.

Phases of Venus Since Venus is an interior planet, it shows phases when viewed with a telescope from the perspective of Earth. Since Venus is an interior planet, it shows phases when viewed with a telescope from the perspective of Earth. Galileo's observation of this phenomenon was important evidence in favor of Copernicus's heliocentric theory of the solar system. Galileo's observation of this phenomenon was important evidence in favor of Copernicus's heliocentric theory of the solar system.

Phases of Venus

Rotation of Venus 243 Earth days = 1 Venus day Retrograde (it rotates in an east to west direction). The periods of Venus' rotation and of its orbit are synchronized such that it always presents the same face toward Earth.

Similar to Earth Venus is sometimes regarded as Earth's sister planet. In some ways they are very similar: Venus is only slightly smaller than Earth (95% of Earth's diameter, 80% of Earth's mass). Both have few craters indicating relatively young surfaces. Their densities and chemical compositions are similar.

Atmosphere The pressure of Venus' atmosphere at the surface is 90 atmospheres (about the same as the pressure at a depth of 1 km in Earth's oceans). It is composed mostly of carbon dioxide. There are several layers of clouds many kilometers thick composed of sulfuric acid. The pressure of Venus' atmosphere at the surface is 90 atmospheres (about the same as the pressure at a depth of 1 km in Earth's oceans). It is composed mostly of carbon dioxide. There are several layers of clouds many kilometers thick composed of sulfuric acid.

Atmosphere

Temperature on Venus This dense atmosphere produces a run-away greenhouse effect that raises Venus' surface temperature by about 400 degrees to over 740 K (hot enough to melt lead). Venus' surface is actually hotter than Mercury's despite being nearly twice as far from the Sun.

Geology of Venus Data from Magellan's imaging radar shows that much of the surface of Venus is covered by lava flows. There are several large shield volcanoes such as Sif Mons. Data from Magellan's imaging radar shows that much of the surface of Venus is covered by lava flows. There are several large shield volcanoes such as Sif Mons.

Geology of Venus The interior of Venus is probably very similar to that of Earth: an iron core about 3000 km in radius a molten rocky mantle comprising the majority of the planet. Recent results from the Magellan gravity data indicate that Venus' crust is stronger and thicker than had previously been assumed.

Geology of Venus Like Earth, convection in the mantle produces stress on the surface which is relieved in many relatively small regions instead of being concentrated at plate boundaries as is the case on Earth.

Moons There are no known moons around Venus There are no known moons around Venus

Mars

Size of Mars Mars is the fourth planet from the Sun and the seventh largest: Diameter: 6,794 km Mass: e23 kg Mars is the fourth planet from the Sun and the seventh largest: Diameter: 6,794 km Mass: e23 kg

Distance to the Sun Orbit: 227,940,000 km (1.52 AU) from Sun Orbit: 227,940,000 km (1.52 AU) from Sun

Orbit and Temperature of Mars Very elliptical orbit that causes drastic temperature changes from aphelion to perihelion Very elliptical orbit that causes drastic temperature changes from aphelion to perihelion Martian surface temperatures range widely from as little as 140 K (-133 C, -207 F) at the winter pole to almost 300 K (27 C, 80 F) on the day side during summer.

Atmosphere of Mars Mars has a very thin atmosphere composed mostly of the tiny amount of remaining carbon dioxide (95.3%) plus nitrogen (2.7%), argon (1.6%) and traces of oxygen (0.15%) and water (0.03%). Mars is unable to recycle any of this carbon dioxide back into its atmosphere and so cannot sustain a significant greenhouse effect. The surface of Mars is therefore much colder than the Earth would be at that distance from the Sun.

Geology of Mars Valles Marineris: a system of canyons 4000 km long and from 2 to 7 km deep Valles Marineris: a system of canyons 4000 km long and from 2 to 7 km deep

Olympus Mons: the largest mountain in the Solar System rising 24 km (78,000 ft.) above the surrounding plain. Its base is more than 500 km in diameter and is rimmed by a cliff 6 km (20,000 ft) high Olympus Mons: the largest mountain in the Solar System rising 24 km (78,000 ft.) above the surrounding plain. Its base is more than 500 km in diameter and is rimmed by a cliff 6 km (20,000 ft) high

There is very clear evidence of erosion in many places on Mars including large floods and small river systems At some time in the past there was clearly some sort of fluid on the surface. There is very clear evidence of erosion in many places on Mars including large floods and small river systems At some time in the past there was clearly some sort of fluid on the surface.

Surface Dunes

Moons of Mars Mars has two tiny satellites which orbit very close to the surface: Distance Radius Mass Satellite (000 km) (km) (kg) Discoverer Date Phobos e16 Hall 1877 Deimos e15 Hall 1877 Mars has two tiny satellites which orbit very close to the surface: Distance Radius Mass Satellite (000 km) (km) (kg) Discoverer Date Phobos e16 Hall 1877 Deimos e15 Hall 1877