What Is the Planet Next to the Sun
The planet next to the Sun is Mercury, the closest planet to our star in the solar system. Mercury orbits the Sun at an average distance of about 57.9 million kilometers, making it the innermost planet in the solar system.
Mercury is a small rocky world with a diameter of 4,879 kilometers, roughly 38 percent of Earth's diameter. It has no atmosphere to retain heat, resulting in extreme surface temperature swings from about 430 degrees Celsius during the day to minus 180 degrees Celsius at night.
Key Facts About Mercury
Mercury completes one orbit around the Sun in 88 Earth days, the shortest year of any planet in the solar system. Its day-night cycle is extreme because it rotates very slowly, with a solar day lasting about 176 Earth days.
The planet has a large iron core that generates a weak magnetic field, about 1 percent as strong as Earth's. NASA's MESSENGER mission, which orbited Mercury from 2011 to 2015, mapped the surface and confirmed the presence of water ice in permanently shadowed polar craters.
Orbital and Physical Characteristics
Mercury's orbit is highly elliptical, bringing it as close as 46 million kilometers and as far as 70 million kilometers from the Sun. Its surface is heavily cratered, resembling the Moon, with vast plains and steep cliffs called lobate scarps.
Exploration and Missions
Only two spacecraft have visited Mercury: Mariner 10 in 1974 and 1975, and MESSENGER, which provided detailed data on its geology and magnetic field. The European Space Agency's BepiColombo mission, launched in 2018, is currently en route and expected to enter Mercury orbit in 2026.
Why Mercury Matters for Science
Studying Mercury helps scientists understand planetary formation, extreme environments, and the evolution of rocky planets. Its proximity to the Sun and unique properties make it a key subject for comparative planetology and solar system research.
Mercury in the Context of the Inner Solar System
Mercury is the first planet from the Sun, followed by Venus, Earth, and Mars. Its position and characteristics are fundamental to understanding the structure and dynamics of the inner solar system.
For more details on Mercury and the solar system, visit NASA's official site. Additional mission data and research can be found on ESA's website.