Its about the solar system notes

1. THE SOLAR SYSTEM
The solar system is the assemblage of the celestial bodies in the outer space. It
comprises the Sun, eight planets, their moons, and other celestial bodies such as asteroids and
comets. It is one of the millions of stellar systems in the Earth’s galaxy or nebula known as the
Milky Way.
Components of the solar system:
Sun
The heart and the star at the center of the Solar System, the Sun is a massive, glowing
ball of hot gases. It provides the gravitational pull that keeps the planet system’s, moons, and
other bodies in orbit. It consists of 70% hydrogen, 28% helium and remaining 2% for carbon,
oxygen, iron, neon and other elements. The Sun’s energy, through processes such as
photosynthesis is also the primary driver of life on Earth.
Planets
They are spherical objects that circle around the sun and are massive or dominant in
their region of space. There are 8 planets (formerly 9).
3 categories:
1. Inner planets/Terrestrial planets – Mercury, Venus, Earth and Mars.
2. Outer planets/Jovian planets/Gas Giants – Jupiter, Saturn, Uranus and Neptune.
3. Dwarf planets – Pluto, Eris, Haumea, Makemake, and Ceres
Mercury
• It is the innermost of the solar system and the eighth in size and mass. Mercury
experiences extreme in temperatures and has heavily cratered surface similar Earth’s
Moon.
• Smallest planet, with a rocky surface covered in craters.
• Name after the Roman messenger god, Mercury, known for his speed.
• Nearly 23% of Mercury’s mass is contained in its largely iron core, which extends from
the planets center to a radius.
PLANETARY DATA:
 Mean distance from the sun: 57,909,227 km (0.39 AU)
 Revolution Period: 87. 97 Earth days
 Rotation Period: 58.646 Earth days
 Atmospheric composition:
 Helium, Hydrogen and Oxygen which are primarily derived from the solar wind and
surface materials.
 Number of Moon/s: 0

2. Importance: Mercury helps scientists understand the formation and evolution of rocky planets.
It’s proximity to the Sun also provide insight into solar interactions with planetary atmospheres
and surfaces.
Venus
• The second planet from the sun and sixth in the solar system in size and mass.
• Known for it’s thick, toxic atmosphere of carbon dioxide and sulfuric acid clouds, Venus
is the hottest planet in the Solar System due to a runaway greenhouse effect.
• Named after Venus, the Roman goddess of love and beauty, due to its bright and
shining appearance in the sky.
PLANETARY DATA
 Mean distance from the sun: 108,209,475 km (0.72 AU)
 Revolution Period: 224.7 Earth days
 Rotation Period: 243 Earth days (retrograde)
 Atmospheric composition: 96% carbon dioxide; 3.5% nitrogen; 0.02% water; trace
quantities of carbon monoxide, molecular oxygen, sulfur dioxide, hydrogen chloride and
other gases.
 Number of Moon/s: 0
Importance: Studying Venus help scientist understand atmospheric dynamics and climate
change. It also provides a comparison for Earth-like planets in other solar system.
Earth
 Third planet from the sun and the fifth largest planet in the solar system in terms of size
and mass
• The only planet known to support life, Earth has a diverse climate, liquid water and the
atmosphere rich in oxygen and nitrogen.
• Earth surface is composed of continents and oceans, with varying terrains such as
mountains, valleys, and plains.
• The name “Earth” comes from Old English and Germanic words meaning “ground” or
“soil”.
PLANETARY DATA
 Mean distance from the sun: 149,598,262 km (1.0 AU)
 Revolution Period: 365. 256 days
 Rotation Period: 23.9345 hrs. (23hr 56 min 4 sec) of mean solar time

3.  Atmospheric composition: molecular nitrogen 78%; 21% molecular oxygen, 0.93%
argon; 0.0395% carbon dioxide (presently rising); water about 1% (variable).
Mars
 The fourth planet in the solar system in order of distance from the sun and seventh in
size and mass.
 Its 2 moons are; Phobos (Greek: Fear) and Deimos (Terror) named after the two sons of
Ares and Aphrodite.
 The planet is named after the Roman God of war, Mars.
• Also known as the Red Planet due to its iron oxide-rich surface. It has a thin
atmosphere, primarily composed of carbon dioxide.
• Has the tallest volcano (Olympus Mons) and the deepest canyon (Valles Marineris) in
the Solar System.
PLANETARY DATA
 Mean distance from the sun: 227,943,824 km (1.5 AU)
 Revolution Period: 686.98 Earth days
 Rotation Period: 24hr 37min 22.663 sec
 Atmospheric 95% carbon composition: dioxide; the remaining components include
mostly diatomic nitrogen with traces of water vapor also present.
 Number of Moon/s: 2
Importance: Mars is a key target for exploring the potential for past or present life and the
possibility of human colonization. It offers valuable insights into planetary geology and climate.
Jupiter
 The most massive planet of the solar system and the fifth in distance from the sun.
 Jupiter is made almost entirely of 2 elements; hydrogen and helium and its mean density
is not much more than the density of water. It has an internal heat source; it emits more
energy than it receives from the sun. It is also the source of intense bursts of radio noise,
occasionally radiating more energy than the sun.
 Known for its Great Red Spot, a giant storm, and its many moons, including the four
largest: Io, Europa, Ganymede, and Callisto.
• Named after Jupiter, the king of the Roman gods, reflecting it’s status as the largest and
most massive planet in our solar system.

4. PLANETARY DATA
 Mean distance from the sun: 778,340,821 km (5.2 AU)
 Revolution Period: 11.86 Earth days
 Rotation Period: 9.9 hours (once a day)
 Atmospheric Composition: 86.4% hydrogen; helium 13.56%; methane 0.21%; ammonia
0.07% and hydrogen sulfide 0.007% and other traces of gases and non-equilibrium
species like phosphine and arsine.
 Number of Moons: 95
Importance: Jupiter immense gravity influences the orbits of other objects in the solar system,
providing stability. Its study helps scientists understand the formation of gas giants and
planetary systems.
Saturn
 It is the second largest planet in the solar system and the sixth nearest planet in distance
to the sun.
 It is noted to be the slowest-moving planet and occupies almost 60 percent of Jupiter’s
volume but has only about 1/3 of its mass and the lowest mean density.
 Known for its stunning ring system, Saturn has a composition similar to Jupiter and more
than 80 moons, including Titan, its largest moon, which has a thick atmosphere.
 Named after the Roman god of agriculture, Saturn.
PLANETARY DATA
 Mean distance from the sun: 1,426,666,000 km (9.5 AU)
 Revolution Period: 29.45 Earth years
 Rotation Period: 10 hr 39min 24 sec
 Atmospheric composition: Helium 18-25% of the atmosphere by mass with the
remaining being mostly molecular hydrogen.
 Number of Moons: 82
Importance: Saturn rings and moons offer valuable insights into planetary formation and the
potential for diverse environments in the outer Solar System. Titan in particular, is the interest
for its Earth-like features.

5. Uranus
 Discovered on March 13, 1781 by the English astronomer William Herschel with the aid
of the telescope.
 Seventh planet in distance from the sun and the least massive of the solar system’s four
giant planets.
• An ice giant with a blue-green hue due to methane in its atmosphere
• It rotates on its side, making its axial tilt unique among the planets.
• Named after the ancient Greek deity of the sky, Uranus.
PLANETARY DATA
 Mean distance from the sun: 2,870,658,000 km (19.2 AU)
 Revolution Period: 84.02 Earth days
 Rotation Period: 17hr 14min (retrograde)
 Atmospheric Composition: Hydrogen, Helium and 2.3% of Methane that is present in the
atmosphere absorbing near-infrared light, giving Uranus its blue-green color.
 Number of Moons: 27
Importance: Uranus unusual rotation and atmospheric composition provide clues about the
dynamics and evolution of planetary systems. It helps us understand the behavior of ice giants.
Neptune
 Third most massive planet in the solar system and the eighth and the outermost planet
from the sun.
 Almost four times the size of Earth but slightly smaller than Uranus.
 An ice giant, with strong winds and storms, including its famed “Great Dark Spot”.
 Named after the Roman god of the sea, Neptune.
PLANETARY DATA
 Mean distance from the sun: 4,498,396,000 km (30.1 AU)
 Revolution Period: 164.79 Earth days
 Rotation Period: 16hr 7min
 Atmospheric composition:
 Composed of hydrogen and helium which together made up nearly 98% of the
atmospheric molecules near the one-bar pressure level. Methane gas constitutes most
of the remaining molecules.

6. Importance: Studying Neptune helps us understand the outer reaches of the Solar System and
the behavior of ice giants. It provides insights into atmospheric dynamics and planetary
formation.
Pluto (dwarf planet)
 Distant member of the solar system that was formerly regarded as the outermost
smallest planet.
PLANETARY DATA
 Mean distance from the sun: 5,910,000,000 km (39.5 AU)
 Revolution Period: 247.69 Earth days
 Rotation Period: 153.3 hours
 Atmospheric composition: Nitrogen, with small amount of methane, carbon monoxide
and hydrogen cyanide
 No. of Moon: 5
Other members of the solar system:
1. Asteroids
Any host of small bodies, about 1000 km (600 miles) or less in diameter, that
orbit the sun primarily between the orbits of Mars and Jupiter. They are remnants from
the Solar System’s formation and offer clues about it’s early history. They are Also called
as minor planets. The first asteroid was discovered on January 01, 1801 by the
astronomer Guiseppe Piazzi at Patermo, Italy.
2. Comets
They are icy bodies that release gas and dust when they come close to the Sun,
creating spectacular tails. They originate from the Kuiper Belt and the Oort Cloud.
VISIBLE PARTS:
 Nucleus: solid body made of volatile ices.
 Coma: freely escaping atmosphere around the nucleus.
 Ion tail: forms from the volatile gases in the coma when they are ionized by
ultraviolet photons from the sun.
 Dust tail: forms from the dust particles that are intimately mixed with the frozen
ices in the nucleus.
3. Meteorite
Fairly small natural object from interplanetary space that survives its passage
through Earth’s atmosphere and lands on the surface. The largest meteorite that has
been identified on Earth was found at 1920 in Nambia and was named as Hoba
Meteorite. The smallest meteorites are called micrometeorites.

7. 4. Satellite
It is a natural object (moon) or spacecraft (artificial satellite) orbiting a larger
astronomical body. The satellites differ significantly in composition. The first artificial
satellite to be placed in orbit was the unmanned Sputnik I launched on October 04,
1957 by the Soviet Union.
The Solar System is a dynamic and diverse collection of celestial bodies, each with
unique characteristics and mysteries. Its study not only enhances our knowledge of the universe
but also inspires technological progress and a deeper appreciation for the delicate balance that
allows life to thrive on Earth. As we continue to explore, the Solar System will undoubtedly
reveal even more wonders and insights into the nature of our cosmic neighborhood. Studying
the Solar System is crucial for several reasons:
1. Scientific Exploration
o studying the Solar System help us understand the formation and evolution of
planetary systems, the potential for life beyond Earth, and the fundamental laws
of physics and chemistry.
2. Life on Earth
o the Solar System’s dynamics directly influence Earth’s climate, tides, and life
cycle. The Sun’s energy sustains all life, while the gravitational interactions with
other celestial bodies shape our environment.
3. Technological Advancements
o space exploration has driven technological innovations in communications,
materials science, and engineering, that benefit various aspects of life on Earth.