A planet is a solid heavenly body that revolves around a star (such as the sun) in a closed elliptical path. It has no light of its own and shines by reflecting the light of the star.

How many major planets are there in our solar system?

There are 8 major planets in our solar system, including Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

What are terrestrial planets?

Terrestrial planets are the four planets closest to the Sun: Mercury, Venus, Earth, and Mars. They have a thin, rocky crust, a mantle rich in iron and magnesium, a core of heavy metals, and a thin atmosphere.

What are Jovian planets?

Jovian planets, also known as gas giants, include Jupiter, Saturn, Uranus, and Neptune. These planets are gaseous, have a ring system around them, and numerous natural satellites (moons).

Why do planets shine?

Planets shine because they reflect the light of their star, such as the Sun, rather than producing their own light.

What is the International Astronomical Union's (IAU) definition of a planet?

The IAU defines a planet as a celestial body that orbits the Sun, has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and has cleared its orbit of other debris.

Why is Pluto considered a dwarf planet?

Pluto is considered a dwarf planet because, while it orbits the Sun and is nearly round in shape, it has not cleared its neighboring region of other objects.

What is the order of planets from the Sun?

The order of the planets from the Sun is: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

Which is the largest planet in our solar system?

Jupiter is the largest planet in our solar system.

What is the smallest planet in our solar system?

Mercury is the smallest planet in our solar system.

What are the key features of terrestrial planets?

Terrestrial planets have a thin, rocky crust, a mantle rich in iron and magnesium, a core of heavy metals, thin atmospheres, and very few moons. They often feature varied terrain such as volcanoes and mountains.

What are the key features of Jovian planets?

Jovian planets are gaseous, have ring systems, and many moons. They are larger and have a lower density compared to terrestrial planets.

Do all planets have moons?

Not all planets have moons. For example, Mercury and Venus do not have any moons, while other planets have multiple moons.

What is the escape velocity of Earth?

The escape velocity of Earth is approximately 11.2 km/s.

What is the rotation period of Jupiter?

The rotation period of Jupiter is approximately 9.9 hours.

What is the orbital period of Neptune?

The orbital period of Neptune is approximately 59,800 days (about 164.8 Earth years).

What is the diameter of Saturn?

The diameter of Saturn is approximately 120,536 km.

What is the axial tilt of Uranus?

The axial tilt of Uranus is approximately 97.8 degrees, which causes it to appear to rotate on its side.

How many moons does Mars have?

Mars has two moons: Phobos and Deimos.

What is the surface temperature of Venus?

The surface temperature of Venus is approximately 464°C, making it the hottest planet in our solar system.

What is the orbital velocity of Mercury?

The orbital velocity of Mercury is approximately 47.9 km/s.

Does Pluto have a ring system?

No, Pluto does not have a ring system.

What is the length of a day on Venus?

A day on Venus, or its rotation period, is about 2802 hours (around 116.75 Earth days).

Which planet has the most moons?

Jupiter has the most moons, with 67 known moons.

What is the perihelion distance of Earth?

The perihelion distance of Earth (the closest point to the Sun) is approximately 147.1 million km.

What is the aphelion distance of Neptune?

The aphelion distance of Neptune (the farthest point from the Sun) is approximately 4545.7 million km.

Does Earth have a global magnetic field?

Yes, Earth has a global magnetic field.

What is the mean temperature on Mars?

The mean temperature on Mars is approximately -65°C.

Which planet has a day longer than its year?

Venus has a day (rotation period) longer than its year (orbital period) due to its slow rotation and retrograde rotation direction.

What is the orbital inclination of Pluto?

The orbital inclination of Pluto is approximately 17.2 degrees.

What are the surface conditions like on Jupiter?

Jupiter's surface conditions are characterized by extremely high atmospheric pressure, strong winds, and a predominantly gaseous composition, with no solid surface.

How does Uranus's axial tilt affect its seasons?

Uranus's extreme axial tilt (97.8 degrees) causes extreme seasonal variations, with each pole experiencing 42 years of continuous sunlight followed by 42 years of darkness.

What is the surface pressure on Venus?

The surface pressure on Venus is about 92 bars, much higher than Earth's, due to its thick carbon dioxide atmosphere.

Which planet has the fastest winds in the solar system?

Neptune has the fastest winds in the solar system, reaching speeds of up to 2,100 km/h.

What is the mean density of Saturn?

The mean density of Saturn is approximately 687 kg/m³, making it the least dense planet in our solar system.

What is the escape velocity of Neptune?

The escape velocity of Neptune is approximately 23.5 km/s.

What are ring systems made of?

Ring systems are typically made up of countless small particles of ice, rock, and dust, which can range in size from micrometers to meters.

How does Earth's magnetic field protect the planet?

Earth's magnetic field protects the planet by deflecting harmful solar wind and cosmic rays, preventing them from stripping away the atmosphere and causing damage to living organisms.

The Solar System: Planets, Definitions, and Classifications

What are Planets?

Planets are solid celestial bodies that revolve around a star, such as the Sun, in elliptical orbits. Composed of rock and metal, they do not emit their own light but shine by reflecting sunlight. Unlike stars, planets are closer to Earth and do not twinkle at night. They move from west to east around the Sun, causing their positions to change daily. Planets are much smaller than the Sun or stars. There are eight major planets in our Solar System.

Planets and dwarf planets of our solar system (Milky Way)

List of Planets in the Solar System (in order of increasing distance from the Sun):

Mercury (Budha): Nearest to the Sun.
Venus (Shukra)
Earth (Prithvi)
Mars (Mangal)
Jupiter (Brihaspati): The largest planet.
Saturn (Shani)
Uranus (Arun)
Neptune (Varun)

IAU Definition of a Planet

In 2006, the International Astronomical Union (IAU) defined a planet in the Solar System as a celestial body that:

Is in orbit around the Sun,
Has sufficient mass to assume hydrostatic equilibrium (a nearly round shape),
Has “cleared the neighborhood” around its orbit, making it the dominant gravitational body in its orbit.

A celestial body that meets the first two criteria but not the third is classified as a dwarf planet. For example, Pluto is considered a dwarf planet because it has not cleared its orbit.

Classification of Planets

Terrestrial Planets

The four planets closest to the Sun—Mercury, Venus, Earth, and Mars—are known as terrestrial planets due to their Earth-like structure. Common features of terrestrial planets include:

Thin, rocky crusts
Mantles rich in iron and magnesium
Cores of heavy metals
Thin atmospheres
Few or no natural satellites
Varied terrains such as volcanoes, canyons, mountains, and craters

Jovian Planets

The planets beyond Mars—Jupiter, Saturn, Uranus, and Neptune—are called Jovian planets, as their structure resembles that of Jupiter. Common features of Jovian planets include:

Being gaseous bodies
Possessing ring systems
Having a large number of natural satellites

The Solar System: Planets, Definitions, and Classifications — Reference = NASA

	Sun	MERC URY	VEN US	EAR TH	MO ON	MA RS	JUPIT ER	SATU RN	URAN US	NEPT UNE	PLUT O
Mass (10²⁴k)	1,988, 500	0.33	4.87	5.97	0.07 3	0.6 42	1898	568	86.8	102	0.013 1
Diameter (k m)	1,392, 684	4879	12,1 04	12,7 56	347 5	679 2	142,9 84	120,5 36	51,11 8	49,52 8	2390
Density (kg/ m3)	1,408	5427	524 3	551 4	334 0	393 3	1326	687	1271	1638	1830
Gravity (m/s 2)		3.7	8.9	9.8	1.6	3.7	23.1	9	8.7	11	0.6
Escape Velocity (km/ s)		4.3	10.4	11.2	2.4	5	59.5	35.5	21.3	23.5	1.1
Rotation Period (hour s)		1407. 6	– 583 2.5	23.9	655. 7	24. 6	9.9	10.7	-17.2	16.1	– 153.3
Length of Day (hours)		4222. 6	280 2	24	708. 7	24. 7	9.9	10.7	17.2	16.1	153.3
Distance from Sun (106 km)		57.9	108. 2	149. 6	0.38 4	227 .9	778.6	1433. 5	2872. 5	4495. 1	5870
Perihelion (1 06 km)		46	107. 5	147. 1	0.36 3	206 .6	740.5		2741. 3	4444. 5	4435
Aphelion (10 6 km)		69.8	108. 9	152. 1	0.40 6	249 .2		1514. 5	3003. 6	4545. 7	7304. 3
Orbital Period (days)		88	224. 7	365. 2	27.3	687	4331	10,74 7	30,58 9	59,80 0	90,58 8
Orbital Velocity (km/ s)		47.9	35	29.8	1	24. 1	13.1	9.7	6.8	5.4	4.7
Orbital Inclination (d egrees)		7	3.4	0	5.1	1.9	1.3	2.5	0.8	1.8	17.2
Orbital Eccentricity		0.205	0.00 7	0.01 7	0.05 5	0.0 94	0.049	0.057	0.046	0.011	0.244
Axial Tilt (degrees)		0.01	177. 4	23.4	6.7	25. 2	3.1	26.7	97.8	28.3	122.5
Mean Temperature (C)		167	464	15	-20	-65	-110	-140	-195	-200	-225
Surface Pressure (bar s)		0	92	1	0	0.0 1	Unkn own	Unkn own	Unkn own	Unkn own	0
Number of Moons		0	0	1	0	2	67	62	27	14	5
Ring System?		No	No	No	No	No	Yes	Yes	Yes	Yes	No
Global Magnetic Field?		Yes	No	Yes	No	No	Yes	Yes	Yes	Yes	Unkn own