SOLAR SYSTEMMade by Jahnvi Tanwar

The Solar systemAmong the thousands of stars that make up Milky Way the Sun is the medium sized star located on the edge of the galaxy. This unique star and the planets that revolve around it, make up what we call the Solar System. It comprises eight planets, their moons and a band of rocky remains that form the Asteroid Belt. The Asteroid belt sits between the orbits of the planets Jupiter and Mars.

The formation of the solar system is believed to have begun billions and billions of years ago. Before the solar system came into existence, scientists believe that there was a giant cloud of dust and gas. This massive cloud was believed to have been disturbed probably by the explosion of a nearby star. This caused the dust and gas to collapse due to the pull of gravity. As it did so, it began spinning in a giant circle. It grew hotter and denser at the centre. At the center of this rotating cloud, a small star came to be formed. This grew bigger and bigger, collecting more dust and more gas. This star became the Sun. Further away, smaller clumps of dust and gas left over from the Sun’s formation were also collapsing. These clumps soon formed into planets.

The Sun

The Sun is the star at the center of the solar system. It is about five billions year old and will continue to shine for about another five billion years. It is by far the most important source of energy for life on Earth. The Sun is a nearly spherical ball of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. The diameter of the Sun is about 109 times that of Earth, and it has a mass about 330,000 times that of Earth, accounting for about 99.86% of the total mass of the Solar System. Chemically, about three quarters of the Sun's mass consists of hydrogen, whereas the rest is mostly helium, and much smaller quantities of heavier elements, including oxygen, carbon, neon and iron.

The Sun

Solar Eclipse

External Features And Internal Surface Of The Sun

Sun Spot

A planet is a large object that revolves or orbits around a star, also reflecting that star’s light. The solar system is made up of several small systems known as planetary system. Every one of these systems is made up of a planet and one or more moons revolving around it. Classification of planets:

• Dwarf planets• Gaseous planets• Rocky planet

Planets of the solar system

Dwarf Planet

Dwarf planets are round objects orbiting the Sun. They are similar to the Solar System’s eight planets, but they are smaller in size and are not moons. Pluto, Ceres, Haumea, Iris and Makemake are the first members as classified as dwarf planet. Hundreds more are yet to be identified.

Gaseous Planet

The Gaseous planets are mostly composed made up of gases, mainly hydrogen and helium as the main part of their composition. They are mostly surrounded by rings and moons.

Rocky Planet

The rocky planets are mostly made up of rock an metal. These planets are very heavy and move slowly. They also don’t have rings.

Mercury is the smallest and closest to the Sun of the eight planets in the Solar System, with an orbital period of about 88 Earth days. Seen from Earth, it appears to move around its orbit in about 116 days, which is much faster than any other planet. It has no known natural satellites. The planet is named after the Roman deity Mercury, the messenger to the gods.Because it has almost no atmosphere to retain heat, Mercury's surface experiences the greatest temperature variation of all the planets, ranging from 100 K (−173 °C; −280 °F) at night to 700 K (427 °C; 800 °F) during the day at some equatorial regions. The poles are constantly below 180 K (−93 °C; −136 °F). Mercury's axis has the smallest tilt of any of the Solar System's planets (about 1⁄30of a degree), but it has the largest orbital eccentricity. As such it does not experience seasons in the same way as most other planets such as Earth. At aphelion, Mercury is about 1.5 times as far from the Sun as it is at perihelion. Mercury's surface is heavily cratered and similar in appearance to the Moon, indicating that it has been geologically inactive for billions of years.

Mercury

VenusVenus is the second planet from the Sun, orbiting it every 224.7Earth days. It has no natural satellite. It is named after the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows. Because Venus is an inferior planet from Earth, it never appears to venture far from the Sun: its elongation reaches a maximum of 47.8°.Venus is a terrestrial planet and is sometimes called Earth's "sister planet" because of their similar size, mass, proximity to the Sun and bulk composition. However, it has also been shown to be radically different from Earth in other respects. It has the densest atmosphere of the four terrestrial planets. The atmospheric pressure at the planet's surface is 92 times that of Earth's. With a mean surface temperature of 735 K Venus is by far the hottest planet in the Solar System, even though Mercury is closer to the Sun. Venus has no carbon cycle that puts carbon into rock, nor does it seem to have any organic life to absorb carbon in biomass. Venus is shrouded by an opaque layer of highly reflective clouds of sulphuric acid, preventing its surface from being seen from space in visible light. It may have possessed oceans in the past, but these would have vaporized as the temperature rose due to a runaway greenhouse effect. The water has most probably photo dissociated, and, because of the lack of a planetary magnetic field, the free hydrogen has been swept into interplanetary space by the solar wind. Venus' surface is a dry deserts cape interspersed with slab-like rocks and periodically refreshed by volcanism.

Tilt And Rotation Of VenusVenusian Crater

Internal Structure Of Venus

EarthEarth, also called the world is the third planet from the Sun, the densest planet in the Solar System, the largest of the Solar System's four terrestrial planets and the only astronomical object known to accommodate life. Earth's biodiversity has evolved over hundreds of millions of years, expanding continually except when interrupted by mass extinctions. Although scholars estimate that over 99 percent of all species that ever lived on the planet are extinct, Earth is currently home to 10–14 million species of life, including over 7.2 billion humans who depend upon its biosphere and minerals. Earth's human population is divided among about two hundred sovereign states which interact through diplomacy, conflict, travel, trade and communication media.

External Features And Internal Surface Of The Earth

Tilt And rotation of Earth

MARSMars is the fourth planet from the Sun and the second smallest planet in the Solar System, after Mercury. Named after the Roman god of war, it is often described as the "Red Planet" because their on oxide prevalent on its surface gives it a reddish appearance.[Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts, and polar ice caps of Earth. The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, as is the tilt that produces the seasons. Mars is the site of Olympus Mons, the second highest known mountain within the Solar System (the tallest on a planet), and of Vales Mariners, one of the largest canyons. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature. Mars has two moons, Photos and Demos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Mars Trojan.

Phobos Deimos

Tilt and rotation Of mars

Olympus Mons

Moons Of Mars

JupiterJupiter is the fifth planet from the Sun and the largest planet in the Solar System. It is a gas giant with mass one-thousandth of that of the Sun but is two and a half times the mass of all the other planets in the Solar System combined. Jupiter is a gas giant, along with Saturn. Uranus and Neptune are ice giants. Together, these four planets are sometimes referred to as the Jovian, giant, or outer planets. The planet was known by astronomers of ancient times. The Romans named the planet after the Roman god Jupiter. When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, bright enough to cast shadows, and making it on average the third-brightest object in the night sky after the Moon and Venus.

Jupiter

Rings and Moons of Saturn

Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Named after the Roman god of agriculture, its astronomical symbol ( ) represents the god's sickle. Saturn is a gas giant with an average radius ♄about nine times that of Earth. Although only one-eighth the average density of Earth, with its larger volume Saturn is just over 95 times more massive.Saturn's interior is probably composed of a core of iron, nickel and rock (silicon and oxygen compounds), surrounded by a deep layer of metallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium and an outer gaseous layer. The planet exhibits a pale yellow hue due to ammonia crystals in its upper atmosphere. Electrical current within the metallic hydrogen layer is thought to give rise to Saturn's planetary magnetic field, which is weaker than Earth's, but has a magnetic moment 580 times that of Earth due to Saturn's larger body radius. Saturn's magnetic field strength is around one-twentieth the strength of Jupiter's.

The outer atmosphere is generally bland and lacking in contrast, although long-lived features can appear. Wind speeds on Saturn can reach 1,800 km/h (500 m/s), faster than on Jupiter, but not as fast as those on Neptune.

Saturn

Saturn

Tethys

Enceladus

Dione Mimas

Rings And Moons Of Saturn

UranusUranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. Uranus is similar in composition to Neptune, and both are of different chemical composition to the larger gas giants Jupiter and Saturn. Thus, astronomers sometimes place them in a separate category called "ice giants". Uranus's atmosphere, although similar to Jupiter's and Saturn's in its primary composition of hydrogen and helium, contains more "ices", such as water, ammonia, and methane, along with traces of other hydrocarbons. It is the coldest planetary atmosphere in the Solar System, with a minimum temperature of 49 K (−224.2 °C), and has a complex, layered cloud structure, with water thought to make up the lowest clouds, and methane the uppermost layer of clouds. The interior of Uranus is mainly composed of ices and rock.

Oberon

Umbreil

Ariel Titania

Miranda

Moons And Rings Of Uranus

NeptuneNeptune is the eighth and farthest planet from the Sun in the Solar System. It is the fourth-largest planet by diameter and the third-largest by mass. Among the gaseous planets in the Solar System, Neptune is the most dense. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times the mass of Earth, and not as dense as Neptune. Neptune orbits the Sun at an average distance of 30.1 astronomical units. Named after the Roman god of the sea, its astronomical symbol is . Neptune is similar in composition to Uranus, and both ♆have compositions that differ from those of the larger gas giants, Jupiter and Saturn. Neptune's atmosphere, like Jupiter's and Saturn's, is composed primarily of hydrogen and helium, along with traces of hydrocarbons and possibly nitrogen; it contains a higher proportion of "ices" such as water, ammonia, and methane. Astronomers sometimes categorise Uranus and Neptune as "ice giants" to emphasise this distinction. The interior of Neptune, like that of Uranus, is primarily composed of ices and rock. Perhaps the core has a solid surface, but the temperature would be thousands of degrees and the atmospheric pressure crushing. Traces of methane in the outermost regions in part account for the planet's blue appearance.

Triton Proteus

Moons And Rings Of Uranus

Let’s compare the planets to Earth

A day on :

Mercury = 3 Earth monthsVenus = 117 Earth daysMars = 41 minutes longer

thanan Earth day

Jupiter = 10 Earth hoursSaturn = 10 ½ Earth hoursUranus = 13 ½ Earth hoursNeptune = 18 Earth hoursPluto = 7 Earth days

If you weigh 85 lbs. On Earth, you weigh:

• 32 lbs on Mercury• 77 lbs on Venus• 32 lbs on Mars• 244 lbs on Jupiter• 112 lbs on Saturn• 79 lbs on Uranus• 105 lbs on Neptune• 2.5 lbs on Pluto

The Orbital Speed of the Planets

• Mercury = 30 miles per second• Venus = 22 miles per second• Earth = 19 miles per second• Mars = 15 miles per second• Jupiter = 8 miles per second• Saturn = 6 miles per second• Uranus = 4.2 miles per second• Neptune = 3.3 miles per second• Pluto= 2.9 miles per second

Therefore, the further away from the Sun, the slower the orbital speed.

The Earth has one Moon. How many moons do the other planets have?

• Mercury - 0• Venus - 0• Mars - 2• Jupiter -

17• Saturn -

22• Uranus -

15• Neptune - 2• Pluto - 1

It takes 365 days for Earth to revolve around the Sun.

How long does it take the other planets?

• Mercury - 88 Earth days• Venus - 225 Earth days• Mars - about 2 Earth years• Jupiter - 11.8 Earth years• Saturn - 30 Earth years• Uranus - 84 Earth years• Neptune - 165 Earth years• Pluto - 248 Earth years

Only 5 Dwarf Planets recognized so far but there may be as many as 200

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Pluto, approximatetrue colorPluto, approximatetrue color

Ceres, seen through(Hubble telescope)Ceres, seen through(Hubble telescope)

Haumea, with its 2 moons,Hi‘iaka and Namaka(Artist’s conception)

Haumea, with its 2 moons,Hi‘iaka and Namaka(Artist’s conception)

Makemake,(Artist’s conception)Makemake,(Artist’s conception)

Eris, seen through(Hubble telescope)Eris, seen through(Hubble telescope)

Most asteroids remain in the Asteroid belt between Mars and Jupiter but a few have orbits that cross Earth’s path.

Three asteroids hit the Earth every 1 million years!

Asteroids

Known asteroid impact sites

Asteroid sizes range from 100m to about 1000km

They are composed of carbon or iron and other rocky material.

The Asteroid belt is a group of rocks that appear to have never joined to make a planet. Why do we think this?

•Too little mass to be a planet•Asteroids have different chemical compositions

It’s all Jupiter’s fault…..

Meteoroids

Most meteor showers are the result of the Earth passing through the orbit of a comet which has left debris along its path

interplanetary rocky material smaller than 100m (down to grain size).

•called a meteor as it burns in the Earth’s atmosphere

•if it makes it to the ground, it is a meteorite

Meteor crater near Winslow, AZ - the culprit was probably 50 m across weighing 200,000 tons!

Meteors are rocky - mainly iron and nickelSome contain carbonaceous material - rich in organic materialMeteors are old - 4.5 billion years - based on carbon dating

Meteor showers:Orionid – Oct 21/22Leonid – Nov 18/19Geminid – Dec 14/15

Comets

Dirty snowballs - dust and rock in methane, ammonia and ice

Halley’s Comet in 1986

The nucleus is a few km in diameter

•Cometary orbits take them far beyond Pluto•Many take up to 1 million years to orbit the Sun once!

•Short period comets (< 200 years) (like Halley’s comet)•Short period comets may have originated in the Kuiper belt•Kuiper belt comet gets “kicked” into an eccentric orbit, bringing it into the solar system

•These long period comets probably originate in the Oort cloud