We in the U N I V E R S E

Blog #11

   

The Solar Family

 

Abstracts:

Milky Way, a part of Galaxy, consists of millions of stars including our Sun. Most of the stars have their family, but some do not have. Our Sun has its family known as the Solar System, which comprises of many major, and minor planets, their satellites, dwarf planets, comets, asteroids and meteoroids. These all work in a systematic order. Its formation has taken a long series of very complex processes. In every moment, many stars are created as well as destroyed. Our Sun will also be destroyed after completing its life in billions of years ahead. However, in different age of life of the Sun, the solar family and its every member behave in different manner and finally they all shall contained back into the Sun.

 

Introduction

The Solar System is the gravitationally bounded system of the Sun and the objects within. The largest of them are the eight planets, namely Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune divided into two groups of four planets in each group, known as the inner planets (includes Mercury, Venus, Earth and Mars) and the outer planets (includes Jupiter, Saturn, Uranus and Neptune). The eight planets in order from the sun are four terrestrial planets, also called the inner planets; the two gas giants, Jupiter and Saturn; and two ice giants, Uranus and Neptune. The formation of Solar System Considered to be initiated about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the sun and a protoplanetary disk.

 

 

 

Some important facts about the Solar system

 

Age: 4.568 billion years approximately

Stars: 1 (Sun)

Known natural satellites: 758 (285 planetary, 473 minor planetary)

Known minor planets: 7,298,470

Known comets: 4,586

Identified rounded satellites: 19

 

Known planets:

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

 

Known dwarf planets:

Ceres, Pluto, Haumea, Quaoar, Makemake, Gonggong, Eris and Sedna.

 

Location:

local interstellar cloud, local bubble, Orion- Cygnus Arm, Milky Way

 

Nearest star: a) Proxima Centauri (4.2465 light years) and

                      b) Alpha Centauri (4.344 light years)

 

 Nearest planetary system: Proxima Centauri System

 

 

The Solar Family:

      According to the available data, about 4.6 billion years ago, our sun came into existence, and with time, it created its own family of planets, comets, asteroids, meteoroids and other entities. The planets which are a part of the solar system were formed from the gaseous clouds and dust that remained after the Sun was formed. The planets started to take shape around 4.6 billion years ago i.e. along with the formation of Sun. Some of the dust, pieces of rock and gas particles which were orbiting the Sun smashed against each other and began to heat up until the entire mass melted. As the mass grew, it began large enough to create its own magnetic force and gravity. The force kept the materials safe from flying off into the space again. It also attracted more materials, until the area around became free of debris and the planets started to get its shape. Some materials in this mass that were heavier than others fell towards the center of the mass to become the core. The rest formed the upper layers towards surface likewise, according to their masses and density. The round shape of the planets and other objects took place due to its circular motion on its own axis. All the planets in this solar system were formed in this manner, about one hundred and thirty million years ago; in the same way the planet’s satellites also came into existence. We named the planets of the Solar System as Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Notably, Pluto was considered as a planet earlier; notwithstanding its rotational path, it has been removed from the list of planets in year 2006 and is now considered as a dwarf planet (The detailed reason of this removal shall be discussed later in this chapter).

 

        The four terrestrial planets having solid surface, belong to the inner solar system. Inversely, all the four giants belong to the outer Solar System; and they do not have any definite surface, as they are mainly composed of gases and liquids. Interestingly, 99.86% mass of the solar system is contained in the Sun alone. in the remaining part, 90% of the mass is fulfilled by the combined mass of the Jupiter and Saturn. There is a strong consensus among astronomers that the solar system also has eight dwarf planets, which consists of one asteroid belt object Ceres, four Kuiper belt objects, Pluto, Haumea, Quaoar and Makemake and three scattered disc objects: Gonggong, Eris and Sedna.

 

 

Solar Family: A Fact File

Planets visible to naked eyes: Mercury, Venus, Earth, Mars and Jupiter.

Great planets/super giants: Jupiter, Saturn, Uranus and Neptune.

Inferior planets: Mercury and Venus

Terrestrial planets: Mercury, Venus, Earth and Mars

 

 

Some Important Definitions

 

Comets

        A comet is the cosmic snowball of frozen gases, rock and dust that orbits the sun. When frozen, these are the size of a town. When a comet’s orbit brings it close to the sun, it heats up and spews dust and gases into a giant glowing head larger than most planets.

 

Asteroids

        An asteroid is a minor planet- an object that is neither a true planet nor a comet, but orbits within the inner solar system. They are rocky, metallic or icy bodies with no atmosphere.

 

Meteoroids

        A meteoroid is a small rocky or metallic body in the outer space. Meteoroids are distinguished as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide. Objects smaller than the meteoroids are called micrometeoroids or space dust.

 

Planetary System

        It is a set of gravitationally bound non stellar objects in or out of orbit around a star or a Star’s family system. Generally speaking, systems with one or more planets constitute a planetary system, although such systems may also consist of bodies such as dwarf planets, asteroids, natural satellites, meteoroids, comets, planetesimals and circumstellar discs.

 

Planetesimals

       The minute planets which are under formation of a planet along with many other entities under gravitation.

 

Circumstellar discs

      After a star is formed, the remaining dust and gas is trapped in orbit, forming a rotating disc or torus around the young star.

 

Terrestrial Planets

        The first four planets from the Sun; i.e. Mercury, Venus, Earth and Mars. These planets are mainly composed of rocks and metals. These planets are also known as inner planets.

 

Provisional Moons

        Moons under assumption or research are kept under the category of provisional moons. However, they will be given a proper name when their discoveries are confirmed by additional observations.

 

Rounded Satellites

                    All the other known satellites that are at least the size of Uranus’ Miranda have lapsed into rounded ellipsoids under hydrostatic equilibrium, i.e. they are ‘round satellites’ or ‘rounded satellites’ and are sometimes categorized as the planetary mass moons.

 

Dwarf planets

        A dwarf planet is a small planetary- mass object that directly orbits around the sun, and massive enough to have gravitationally rounded, but is insufficient to achieve an orbital dominance like the eight planets in the solar system. The prototypical dwarf planet is Pluto, which was regarded as the planet before the ‘dwarf planet’ concept was adopted in 2006. 

        The term ‘dwarf planet’ was coined by a planetary scientist: Alan stern as part of a three-way categorization of planetary mass objects in the solar system. Classical planets, dwarf planets and satellite planets. Dwarf planets were thus conceived of as a category of planet. In 2006, however, the concept was adopted but the International Astronomical Union (IAU) as a category of planet and sub planetary objects, part of a three-way re-categorization of bodies orbiting the Sun: planets, dwarf planets and small solar system bodies. Thus Stern and other geologists consider dwarf planets and large satellites to be planets, but since 2006, the IAU and perhaps the majority of astronomers have excluded them from the list of planets.

        The interest of dwarf planets to planetary geologists is that they may be geologically active bodies, an expectation that this concept was borne out in 2015 by the Dawn mission to Ceres and New Horizons mission to Pluto. Astronomers are in general agreement that at least the eight largest candidates are the dwarf planets- in irregular order of size: Pluto, Eris, Haumea, Makemake, Gonggong, Quaoar, Sedna and Ceres.

 

 

Natural Satellites or Satellites

        A natural satellite is in the most common usage, an astronomical body that orbits a planet, dwarf planet, small solar system body or even in some cases; found to orbit around another natural satellite. Natural satellites are colloquially referred to as moons, a derivation from the moon of earth. In our Solar System, there are six planets having at least one moon; with altogether it contains two hundred and eighty-four (284) known natural satellites. Seven objects which are commonly considered as dwarf planets by the astronomers are also known to have natural satellites. These dwarf planets are Pluto, Haumea, Makemake, Gonggong, Salacia, Quaoar and Eris. As per the studies of November 2021, there are four hundred and forty-two (442) other minor planets in the Solar System known to have natural satellites.

        A planet is at least ten thousand (10,000) times heavier by the mass of its any of the natural satellite(s). The Earth and Moon system in the Solar System is a unique exception. The diameter of the Moon is 0.273 times the diameter of the Earth. The mass of the Earth is 80 times the mass of the moon. The next larger ratios are the Neptune and Trion system at 0.055, the Saturn and Titan system at 0.044, the Jupiter and Ganymede system at 0.031. For the dwarf planet category, Charon has the highest ratio being 0.52 the diameter and 12.2% of the mass of Pluto.    

 

 

 

 

Planets

        A planet is a large, rounded, astronomical body that is neither a star nor its remnant. But best available theory of planet formation is the nebular hypothesis, which posits an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion. The Solar System has at least eight planets, the terrestrial as well as the giant ones.

 

        The word planet comes from the Greek word Planetai which means wandering. In antiquity, this word refers to the sun, moon and five points of the light visible to the naked eye that moved across the background of the stars- namely: Mercury, Venus, Mars, Jupiter and Saturn. Planets have historically had religious associations, multiple cultures identified celestial bodies with Gods, and these connections with mythology and folklore persists in the schemes for naming the newly discovered solar system bodies. Earth itself is recognized as a planet when heliocentric theory replaced the geocentric theory in the 16^th and 17^th century.

 

        With the discovery and further development of the telescope, the meaning of planet broadened to include only visible with assistance, the moons of the planets beyond earth; the ice giants- Uranus and Neptune, Ceres and other bodies, later recognized to be a part of the asteroid belt. And then Pluto, found to be the largest member of the collection of icy bodies known as the Kuiper Belt. The discovery of other large objects in the Kuiper Belt, particularly Eris, spurred debate about how exactly to define a planet.

 

        The Indian Astrological theory suggests the nine planets (Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn, Uranus and Neptune) other than Earth which includes all the eight planets of the solar system, based on the theory of Geocentric Arrangement. Theory was established in the post Vedic Age, thousands of years ago. However, the details about the physical being and nature of the planets along with its rotational data and distance from the earth are identical to the data produced by the modern researches.

 

 

An overview of the Planets of the Solar System:

 

Mercury:

Distance from the Sun: 57,909,227 Kilometers

Equatorial Diameter: 4,879.40 Kilometers

Mass: 3.30 X 10²⁰ Tones

Density: 5.43 times that of water

Surface temperature: -173 degree Celsius to +427 degree Celsius

Period of Rotation: 58 days 15 hours 30 minutes

Revolution around the Sun: 87 days 23 hours 17 minutes

Number of known Moons: 0

 

 

Venus

Distance from the Sun: 108,209,475 Kilometers

Equatorial Diameter: 12,103.61 Kilometers

Mass: 4.87 X 10²¹ Tones

Density: 5.24 times that of water

Surface temperature: +462 degree Celsius

Period of Rotation: 243 days 26 hours

Revolution around the Sun: 224 days 16 hours 48 minutes

Number of known Moons: 0

 

 

Earth

Distance from the Sun: 149,598,262 Kilometers

Equatorial Diameter: 12,742 Kilometers

Mass: 5.97 X 10²¹ Tones

Density: 5.51 times that of water

Surface temperature: -88 degree Celsius to +58 degree Celsius

Period of Rotation: 23 days 56 hours

Revolution around the Sun: 1 year (365 days 6 hours14 minutes)

Number of known Moons: 1

 

 

Mars

Distance from the Sun: 227,943,824 Kilometers

Equatorial Diameter: 6,779 Kilometers

Mass: 6.42 X 10²⁰ Tones

Density: 3.93 times that of water

Surface temperature: -87 degree Celsius to -5 degree Celsius

Period of Rotation: 1 day 37 hours

Revolution around the Sun: 1 year 321 days 37 hours

Number of known Moons: 2

 

 

Jupiter

Distance from the Sun: 778,340,821 Kilometers

Equatorial Diameter: 139,822 Kilometers

Mass: 1.90 X 10²⁴ Tones

Density: 1.33 times that of water

Surface temperature: -148 degree Celsius

Period of Rotation: 9 hours 55 minutes

Revolution around the Sun: 11 years 314 days 20 hours

Number of known Moons: 66 (out of 66, 16 are provisional moons)

 

 

Saturn

Distance from the Sun: 1,426,666,422 Kilometers

Equatorial Diameter: 116,464 Kilometers

Mass: 5.68 X10²³ Tones

Density: 0.70 times that of water

Surface temperature: -178 degree Celsius

Period of Rotation: 10 hours39 minutes

Revolution around the Sun: 29 years 163 days 8 hours 5 minutes

Number of known Moons: 62 (out of 62, 9 are provisional moons)

 

 

Uranus

Distance from the Sun: 2,870,658,186 Kilometers

Equatorial Diameter: 50,724 Kilometers

Mass: 8.68 X 10²² Tones

Density: 1.30 times that of water

Surface temperature: -216 degree Celsius

Period of Rotation: 17 hours 14 minutes

Revolution around the Sun: 84 years 6 days 3 hours 34 minutes

Number of known Moons: 27

 

 

Neptune

Distance from the Sun: 4,498,396,441 Kilometers

Equatorial Diameter: 49,244 Kilometers

Mass: 1.02 X 10²³ Tones

Density: 1.64 times that of water

Surface temperature: -214 degree Celsius

Period of Rotation: 16 hours 7 minutes

Revolution around the Sun: 164 years 288 days 50 minutes

Number of known Moons: 13

 

 

Pluto: No Planet Anymore…

       According to the definition set by the IAU, a planet must have its own separate orbit; but Pluto did not have any orbit of its own. In its every orbital cycle of 248 years, it gradually enters in the orbit of the Neptune remains 20 years in that orbit and then comes out to its original path i.e. it intercepts the orbit of Neptune which implies that it does not have its own independent orbit and it is a primary condition for an entity to be a planet. Therefore, its name was ousted from the list of planets in 2006. Lastly, Pluto was roaming in the orbit of the Neptune from 7^th February 1979 to 11^th February 1999.

 

 

 

Table 1: showing the distance from the Sun, number of moons, temperature, number of rings and relative mass to Earth of the planets of the solar system.

Planet	Distance from Sun (EU)	Number of Moons	Temperature in Celsius	Rotational period
Mercury	0.39	0	-170 to 390	58d15h36m
Venus	0.72	0	475	243 d
Earth	1.0	1	22	23h56m
Mars	1.52	2	-23	24h37m
Jupiter	5.2	16	-123	10h
Saturn	9.54	22	-180	10h40m
Uranus	19.2	15	-218	16h
Neptune	30.1	2	-228	18h

  EU = Earth Unit; d days, h hours, m minuts.

 

 

Table 2: showing the color, orbital speed, rotation period and orbital period of the planets of the solar system.

Planets	No. of Rings	Relative Mass	Color	Orbit speed	Orbit period
Mercury	0	0.06	M&E Str	47.9	88d
Venus	0	0.82	M&E Str	35	224.7d
Earth	0	1	Blue	29.8	365.2d
Mars	0	0.11	Red	24.1	1.88y
Jupiter	1	318	Red spot	13.1	11.86y
Saturn	Ex Sys	95	Blackish	9.6	29.46y
Uranus	10	15	Green	6.8	84y
Neptune	1	17	Greenish	5.4	164.8y

M&E Str = Morning and evening Stars

 

Terminology:

        The first known natural satellite was the Moon, but it was considered as a planet until Copernicus, introduced his De revolutionibus orbium coelestium in 1543. Until the discovery of the Galilean satellites in 1610, there was no opportunity for referring to such objects as a class. The first to use the term satellite to describe the orbiting bodies was the German Astronomer Johannes Kepler. He described the orbiting bodies in his pamphlet Narratio de Observatis a se quator louis satellitibus erronibus (Narration About Four Satellites of Jupiter Observed) in 1610. He derived the term from the Latin word Satelles, meaning ‘guard’, ‘attendant’ or ‘companion’ because the satellites accompanied their primary planet throughout their journey.   

 

Conclusion:

       Our Sun has a very rich and interesting story about its formation and creation of the Solar Family. We are fortunate to be a part of our Solar Family as it is rear combination of the matters, atmosphere and environment support life. The nearest stars are the Proxima Centauri with its family, called the Proxima Centauri System and Alpha Centauri without family. The eight planets which orbit around the sun are known as the major planets, whereas some other minor planets are also roaming and revolving inside the solar system.

       Sun is responsible to hold on the entire Solar family to posit its situation and source of energy for the functions of all the terrestrial activities as well as the existence of the life anywhere within. This is why Sun is tribute to be the father of the whole Solar family system.

 

 

 

 

Total words:  3000+

 

Sources of Data:

Wikipedia

Space.com

Amnh.com

Study.com

Science.nasa.gov

Google and other websites

Orient Blackswan School Atlas

Other course materials

Manorama Tell Me Why Earth

Vedanta