PLANETS & DWALF PLANETS IN OUR UNIVERSE

    SCIENCE COMMUNITY

Musati maenderera mberi, zivai kuti:

1. The surface gravity may be expressed in terms of g, where g is the acceleration due to the earth's gravity which is approximately 9.81m/s^2.
2. According to the latest research and the revision of the definition of the term planet in 2006, there are 8 planets in the solar system.

PLANETS IN THE UNIVERSE

MERCURY

• Its orbit period is about 88 Earth days.
• It is tidally or gravitationally locked.
• Geologists have discovered that:

1. The Crust is 100-300km thick.
2. The Mantle is 600km thick.
3. The Core has a 1,800km radius.
4. It is the nearest to the sun.
5. Mercury's surface in appearance is similar to that of the Moon
6. Mercury's axial tilt is almost zero, with the best measured value as low as 0.027degrees.

VENUS

Mass: 4.867×10^24kg

Radius: 6.052km

Orbital Period: 225days

Gravity: 8.87m/s^2

• It is the second planet from the sun.
• It has the longest rotation period (243days) of any planet in the solar system and it rotates in the opposite direction to most other planets.
• It is sometimes nicknamed 'The Earth's Sister Planet.
• Venus has an extremely dense atmosphere composed of 96.5% carbon dioxide (CO2), 3.5% nitrogen (N) and traces of other gases, most notably sulfur dioxide (SO2)

EARTH

Mass: 5.972x10^24 kg

Radius: 6 371km 

Age: 4.543 billion years

Distance from the Sun: 149.6 million km

Orbital Period: 365 days

• It is the third planet from the sun.
• It is the only object in the entire universe known to harbor life.
• It is the densest planet in the Solar System and the largest of the four terrestrial planets.
• The Geologic layers of the Earth:
• Lithosphere:      0-60km
• Crust:                 0-35km
• Upper Mantle:    35-60km
• Mantle:               35-2890km
• Asthenosphere:   100-700km
• Outer Core:         2890-5100km
• Inner Core:          5100-6378km

MARS

Radius: 3 390km

Gravity: 3 711m/s^2

Moons: Phobos & Deimos

• Mars is the 4th planet from the sun and the second smallest planet in the Solar System, after Mercury.
• It is often referred to as the 'Red Planet' because the iron oxide prevalent on its surface gives it a reddish appearance.
• It can be seen by a naked eye from Earth and its reddish coloring is visible too.
• Mars is approximately half the diameter of Earth with a surface area which is only slightly less than the total area of Earth's dry land. 

JUPITER 

Moons: at least 67 (some of them are: Europa, Ganymede, Callisto, lo, Adrastea, Amalthea & Thebe) 

• It is the fifth planet from the sun and the largest in the Solar System.
• Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, though helium comprises only about a tenth of the number of molecules.
• Jupiter has at least 67 moons, including the four large Galilean moons discovered by Galileo Galilei in 1610. 

SATURN 

Radius: 58 232km

Moons: (some of them are: Titan, Enceladus, Mimas, Lapetus, Dione, Tethys & Rhea)

• It is the sixth planet from the sun and the second largest in the solar system after Jupiter.
• It is a gas giant with an average radius of about nine times that of the Earth, although it has 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 comprised of a core of iron, nickel and rock (silicon and oxygen compounds). 

URANUS 

Radius: 25 362km

Moons: (some of the mons are: Titania, Umbriel, Ariel, Miranda, Trinculo, Oberon & Puck)

• It is the seventh planet from the sun.
• Uranus is also refered to by Scientists as an 'Ice Giant'.
• Uranus orbits the sun once every 84 years.
• Its average distance from the sun is roughly 3 billion km (which is about 20AU). 
• It was the first planet to be discovered with a telescope by Sir William Herschel in 1781.
• He announced its discovery on 13 March 1781

NEPTUNE

Length of Day: 0d 16h 6m

Distance from sun: 4.495 billion km

Surface area: 7.618 billion km²

Radius: 24 622 km

Mass: 1.024×10^26 kg (17.15 M⊕)

Density: 1.64 g/cm³

Moons: (some of them are: Triton, Laomedeia, Thalassa, Hlimede, Nereid, Psamathe, Despina, Larissa, Naiad, Sao, Neso, Galatea, Proteus & Hippocamp)

• It is the eighth and the farthest known planet from the sun in the Solar System.
• It is the 4th largest planet by diameter; the third most massive planet and the densest giant planet.
• Neptune orbits the sun once every 164.8 years at an average distance of 30.1 astronomical units (AU) [4.50 × 10^9 km]

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The 2021 Space Conversation: Space Tourism

Musati maenderera mberi, zivai kuti:

1. The surface gravity may be expressed in terms of g, where g is the acceleration due to the earth's gravity which is approximately 9.81m/s^2.

DWALF PLANETS IN THE UNIVERSE

PLUTO

Radius: 1 188.3km

Mass: (1.303 ±0.003)×10^22 kg

Surface Gravity: 0.063g

Orbital Period: 248 Earth days

• It is a dwarf planet found in the Kuiper Belt. The Kuiper Belt is a ring of objects in the outer Solar System, beyond the orbit of Planet Neptune.
• Pluto is the largest object in the Kuiper Belt.
• Pluto is predominantly made of ice and rock.
• Pluto was discovered and first called the ninth planet, in 1930, it was until 2006 when Pluto was considered a dwarf planet after the revision of the definition of the term planet.

CERES

Mean Radius: 469.73km

Mass: (9.3835 ±0.0001)×10^20 kg

Surface Gravity: 0.028g

Orbital Period: 4.6 Earth years (approximately 1 684d)

• Ceres was the first asteroid that was discovered. It was discovered by Giuseppe Piazzi on the 1st of January 1801.
• It is located in the asteroid belt, which is between the orbits of Jupiter and Mars.
• It was initially considered a planet, until in the 1850s, post the discoveries of similar objects in similar orbits, and in 2006 when the term planet was revised and redefined.