- Earth: It is the third planet from the Sun and is the largest of the terrestrial planets in the Solar System, in both diameter and mass. Home to millions of species including humans, Earth is the only place in the universe where life is known to have originated. Scientific evidence indicates that the planet formed 4.54 billion years ago, and life appeared on its surface within a billion years.
- Extrasolar planet, or exoplanet: It is a planet beyond the Solar System. As of March 2008, 277 exoplanets have been detected. The vast majority were detected through various indirect methods rather than actual imaging. Most of them are massive giant planets likely to resemble Jupiter. It is estimated that at least 10% of sun-like stars have planets, and the true proportion may be much higher.
- Inner or Terrestrial planets are Mercury, Venus, Earth, and Mars. The four inner or terrestrial planets have dense, rocky compositions, few or no moons, and no ring systems. They are composed largely of minerals with high melting points, such as the silicates which form their solid crusts and semi-liquid mantles, and metals such as iron and nickel, which form their cores. Three of the four inner planets (Venus, Earth and Mars) have substantial atmospheres; all have impact craters and tectonic surface
- Jupiter, the fifth planet from the Sun and the largest planet within the solar system, two and a half times as massive as all the other planets in our solar system combined. Jupiter, along with Saturn, Uranus and Neptune, is classified as a gas giant. Together, these four planets are sometimes referred to as the Jovian planet.
- Mars, the fourth planet from the Sun in the Solar System, also referred to as the "Red Planet" because of its reddish appearance as seen from Earth. A terrestrial planet with a thin atmosphere, Mars has surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts and polar ice caps of Earth.
- Mercury: It is the innermost and smallest planet in the solar system, orbiting the Sun once every 88 days. Mercury is bright when viewed from Earth, ranging from ?2.0 to 5.5 in apparent magnitude. It can only be seen in morning and evening twilight. Physically, Mercury is similar in appearance to the Moon. It is heavily cratered, has no natural satellites and no substantial atmosphere. It has a large iron core, which generates a magnetic field about 1% as strong as that of the Earth. It is an exceptionally dense planet due to the large size of its core. The surface temperatures on Mercury range from about 90 to 700 K (?180 to 430 °C), with the subsolar point being the hottest and the bottoms of craters near the poles being the coldest.
- Neptune, the eighth planet from the Sun in the Solar System. It is the fourth largest planet by diameter, and the third largest by mass. Neptune is 17 times the mass of Earth. Neptune's atmosphere is primarily composed of hydrogen and helium along with traces of methane. The methane in the atmosphere, in part, accounts for the planet's blue appearance. Neptune also has the strongest winds of any planet in the solar system, measured as high as 2,100 km/h.
- Outer planets or Gas Giants (sometimes called Jovian planets): Together these four planets -Jupiter, Saturn, Uranus and Neptune- make up 99 percent of the mass known to orbit the Sun. Jupiter and Saturn's atmospheres are largely hydrogen and helium. Uranus and Neptune's atmospheres have a higher percentage of "ices", such as water, ammonia and methane. All four gas giants have rings, although only Saturn's ring system is easily observed from Earth.
- Saturn: It is the sixth planet from the Sun and the second largest after Jupiter. Along with the planets Jupiter, Uranus, and Neptune, it is classified as a gas giant (also known as a Jovian planet, after the planet Jupiter). The planet Saturn is primarily composed of hydrogen, with small proportions of helium and trace elements. The interior consists of a small core of rock and ice, surrounded by a thick layer of metallic hydrogen and a gaseous outer layer. Wind speeds on Saturn can reach 1,800 km/h.
- Uranus: It is the seventh planet from the Sun, the third largest and fourth most massive planet in the solar system. Uranus was the first planet discovered in modern times. It is visible to the naked eye. Uranus has a faint planetary ring system, composed of dark particulate matter up to ten meters in diameter. Thirteen distinct rings are presently known, the brightest being the epsilon ring. The matter in the rings may once have been part of a moon which was shattered by a high-speed impact or tidal forces.
- Venus: It is the second-closest planet to the Sun, orbiting it every
224.7 Earth days. It is the brightest natural object in the night sky, except
for the Moon, reaching an apparent magnitude of ?4.6. Because Venus is an
inferior planet, from Earth it never appears to venture far from the Sun:
its elongation reaches a maximum of 47.8°. Venus reaches its maximum
brightness shortly before sunrise or shortly after sunset, for which reason
it is often called the Morning Star or the Evening Star. Classified as a
terrestrial planet, it is sometimes called Earth's "sister planet",
for the two are similar in size, gravity, and bulk composition. Venus is
covered with an opaque layer of highly reflective clouds of sulphuric acid,
preventing its surface from being seen from space in visible light. Venus
has the densest atmosphere of all the terrestrial planets, consisting mostly
of carbon dioxide. The atmospheric pressure at the planet's surface is 92
times that of the Earth.