Physical Geography

Mercury and Venus are the only two recognized planets in our solar system without moons. However, there are many, many planets in the universe and a significant portion of these, if our solar system is assumed representative of at least a significant portion of the universe’s planetary systems likely have no moons.

The nearness of Mercury to the massive gravity influence of the Sun is the likely reason that no natural satellites are present, although it is possible that one or more may have existed in the past.

Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System (after Eris) and the tenth-most-massive body observed directly orbiting the Sun. Originally classified as the ninth planet from the Sun, Pluto was recategorized as a dwarf planet and plutoid owing to the discovery that it is only one of several large bodies within the Kuiper belt.

As the nearest star from our Solar System, Proxima Centauri is a prime candidate for future interstellar travel and space colonization missions. Proxima Centauri is a red dwarf star about 4.24 light-years distant inside the G-cloud in the constellation of Centaurus.

In physics, radiation is a process in which energetic particles or energetic waves travel through vacuum, or through matter-containing media that are not required for their propagation. The Earth receives 174 petawatts (PW) of incoming solar radiation (insolation) at the upper atmosphere.

Venus has a maximum surface temperature of 462°C (862°F) making it the hottest planet in the solar system. The high temperature is because of its dense cloud layer.

The Big Dipper is an asterism consisting of the seven brightest stars of the constellation Ursa Major. In Hindu astronomy, it is referred to as the “Collection of Seven Great Sages” (Saptarshi Mandal), as each star is named after a mythical Hindu sage.

The brightest star in the sky is Sirius, also known as the “Dog Star” or, more officially, Alpha Canis Majoris, for its position in the constellation Canis Major. Sirius is a binary star dominated by a luminous main sequence star, Sirius A, with an apparent magnitude of -1.46.

Eris is the most massive and second-largest dwarf planet known in the Solar System. It is 27% more massive than dwarf planet Pluto. Eris is the ninthmost- massive known body directly orbiting the Sun,

Planet Earth has been called the "Blue Planet" due to the abundant water on its surface. Here on Earth, we take liquid water for granted; after all, our bodies are mostly made of water. However, liquid water is a rare commodity in our solar system.

As Earth moves (rotates) from West to East, so stars appear to be more in West than East. So when we say that stars "move", it could be because of the Earth, because of their own movements, or because of both the Earth takes roughly 24 hours to spin on its axis, moving from east to west.

The largest planet in our solar system by far is Jupiter, which beats out all the other planets in both mass and volume. Jupiter's mass is more than 300 times that of Earth, and its diameter, at 140,000 km, is about 11 times Earth's diameter.

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Johannes Kepler published his first two laws about planetary motion in 1609, having found them by analyzing the astronomical observations of Tycho Brahe.

According to the size of the planets the descending order will be Jupiter (largest planet), Saturn (2nd largest), Uranus (3rd largest) & Neptune (4th Largest).