Most people mistakenly assume Mercury to be Earth’s closest planet – however this is often not accurate; Venus actually tends to be closer.
Our solar system contains eight planets – including Pluto which was recently demoted due to its eccentric orbit. Let’s cover each one in order, starting with Mercury.
Mercury
Mercury, our closest planet to the Sun, orbits an elliptical path that brings it as close to 29 million miles and 43 million miles from Earth, respectively. Mercury is both small and fast; taking just 88 days for each orbit around its path at 112,000mph speeds!
Mercury does not possess a thick atmosphere, but does possess an ultra-thin “exosphere,” composed of atoms blasted off its surface by solar radiation and micrometeoroid impacts, according to NASA. These quickly escape into space creating an outbound trail behind Mercury that extends hundreds of miles long and can even be observed from Earth.
Planet Neptune is the smallest planet in our Solar System and lacks significant moons, though its icy surface has been heavily cratered from comet and asteroid impacts early on in its existence. Since there is no atmosphere, these craters remain undamaged compared to Earth’s Moon; giving it an appearance similar to our Moon, featuring scarps and cliffs with lobe-shaped scarps and scarps.
Mercury, as the Solar System’s smallest terrestrial planet, possesses one of the weakest magnetic fields among them all; yet, the magnetic force holding it in orbit is strong enough to generate magnetic tornadoes which channel solar wind toward Mercury’s surface.
Scientists developed a model of our Solar System with all its planets’ orbits and ran it for thousands of simulated years to calculate distance between any two planets at any point in time – this enabled them to determine that Mercury was indeed closest to every planet in our Solar System, rather than only Venus and Mars as commonly believed.
Mercury has two small, icy moons named Nix and Hydra that were discovered by the Hubble Space Telescope between 2005 and 2011 respectively. Both moons exhibit unique elongated shapes not commonly seen among Solar System moons.
Mercury (Hg) is a heavy metal with the chemical symbol Hg and atomic number 80, found naturally as cinnabar or elemental mercury (Hg(0)). Mercury is often used as an industrial solvent due to its low boiling and melting points; exposure can cause tremors, depression, mood swings, irritability and pins-and-needles sensation in skin, limbs or face.
Venus
Venus, named for the Roman goddess of love and beauty, is another “twin planet” in our Solar System. Like Earth, its size, density, mass, atmosphere, temperature and tides are comparable; however, Venus experiences much hotter temperatures due to being tidally locked for roughly two weeks longer each day than our own day does. With such extreme conditions on its surface and hellish atmosphere it makes Venus unlikely for life to have emerged there; yet scientists believe there may have once been liquid water present there as well.
Venus’ thick atmosphere traps heat, so its temperature approaches 800degF (550degC). Its surface is arid and dry with a crust approximately 50 km thick, mantle thickness 3,000 km thick and core size of 6,000 km wide. Venus is also home to sulfuric acid and carbon dioxide with toxic gases like carbon monoxide, hydrogen sulfide, methane gas as well as other potentially deadly pollutants present.
Due to high temperatures and extreme chemistry, current forms of life cannot thrive on Earth today. Scientists must use different techniques in order to study our planet and learn more about its ability to support microbial life in its past.
Soviet probes discovered whistler mode waves similar to lightning in Venus’ clouds during 1960s missions, suggesting it may still occur, although at a much lower frequency. Furthermore, Venus takes approximately 243 Earth days for rotation on its axis and does not generate magnetic fields like that seen here on Earth.
Project Magellan conducted a radar mapping of Venus with radar, discovering evidence of recent volcanic activity as well as few impact craters indicating any meteoroids striking it would quickly disintegrate or melt in its hot, dense environment. Two-thirds of Venus is covered by flat plains dotted with volcanic eruptions; six mountainous regions were named for women from both myth and reality, such as Ishtar Terra near Australia’s North Pole and Aphrodite Terra across its equator.
Earth
The Earth is one of the most diverse planets in our Solar System, boasting diverse landscapes and ecosystems. Composed of several layers, from its core to the surface: crust, mantle and hydrosphere (primarily oceans). The atmosphere can be divided into several zones including troposphere (where weather occurs), stratosphere (home of Earth-protecting ozone layer), mesosphere and thermosphere – the latter two also being home for meteoroids that burn up or hit ground) before eventually returning back home again.
Antarctica covers 20 percent of Earth’s surface. At 8,850 meters (29,035 feet), Mount Everest in Nepal stands as the world’s highest point. One unique aspect of Earth is its rotation which causes one side to face directly towards the Sun at any given time – thus providing us with day and night cycles on a 24-hour cycle.
Our Earth has one natural satellite, the Moon, which orbits it every 29 days and can be seen with binoculars or telescopes from any point on its surface. Asteroids and comets sometimes pass close by and may occasionally be visible with telescopes as well.
Our Solar System contains eight planets that orbit the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune in order of distance from it. Formerly considered a planet itself, Pluto is now classified as an exoplanet along with asteroids not directly orbiting any Sun-orbiting planet such as Uranus or Neptune.
Answering this question accurately depends upon when you ask it; planets orbit Earth elliptically and may sometimes move closer or further from it than at other times. Therefore, in order to give a definitive answer you would require software which calculates positions of each planet at specific moments in time – using this approach Venus would probably be closest at any given time.
Mars
Mars, the fourth planet from the Sun, is often referred to as Earth’s “brother” due to its similar size, composition and appearance. Much like Earth, Mars features volcanoes and polar ice caps – though due to its elliptical orbit seasons on Mars tend to last much shorter.
Mars boasts some of the tallest mountains and deepest valleys in our solar system, such as Olympus Mons – a 17 mile (27 km) high shield volcano with three times as much height as Mount Everest – as well as Valles Marineris, an expansive system of canyons stretching for over 1,000 miles (1,600 km).
Astronomers have discovered two moons orbiting Mars: Phobos and Deimos. Both moons feature numerous craters and grooves thought to have resulted from impacts, like our moon. Tidally locked with Mars like our own, Phobos and Deimos can always show one face to their parent planet; Phobos is believed to have captured an asteroid at some point; UV light reflecting from its surface supports this claim while Deimos may have been in orbit at its own formation time.
Scientists theorize that Mars features a solid iron core and an igneous rock mantle comprised of basalt. Its crust resembles that of Earth, likely including an andesite layer similar to our own planet’s. Mars also experiences seasonal variations due to its 23.4 degree tilt which changes how much sunlight reaches different parts of its surface resulting in different seasons being experienced on different areas.
Venus, Mercury and Mars are the closest planets to Earth in order. Although their proximity may seem random at first, current models of our Solar System suggest that gas and dust gathered into the Sun first and formed into rocky planets afterward; solar winds then dispersed most of these gases further into space where they formed outer gas giants like Jupiter or Saturn; Venus thus becomes closer than these gas giants which predominantly consist of gases.