Table of Contents
INTRODUCTION
Mercury is the closest planet to the sun and the smallest planet among all of the planets of our solar system. The small planet doesn’t have any moons and rotates around the sun faster than any other planet in the solar system. Mercury is one of the densest planet after Earth with a massive metallic core roughly 3600 to 3800 kilometres wide. Mercury was also given different names because it appeared as both a morning and evening star. However, Greek astronomers recognised that the two names referred to the same entity, and Heraclitus, circa 500 B.C., rightly believed that Mercury and Venus orbited the sun rather than Earth.
PLANET FEATURES
Mercury facts
- Equator circumference: 15,329km
- Radius: 2,440km
- Average distance from Sun: 58 million km/ 0.39 astronomical units (AU)
- Surface temperature: -180°C to 430°C
- Surface gravity: 3.7 m/s2 or 0.38 g0
- Surface area: 7.48 X 107 Km2 or 0.147 Earths
- Volume: 6.083 X 1010 Km3 or 0.056 Earths
- Mass: 3.3011 X 1023 Kg or 0.055 Earths
- Escape Velocity: 4.25 m/s
- Mean density: 5.472 g/cm3
- Day length: 58.7 Earth days
- Year length: 88 Earth days
- Sunlight travel time: 3.2 Minutes
- Average orbital speed: 107,082 mph (47km/s)
- Moons: 0
- Planet type: terrestrial
- Composition: Oxygen, sodium, magnesium, hydrogen, potassium, calcium, helium, iron, aluminium, argon, water vapour, xenon, krypton and neon
HISTORY OF DISCOVERY
Mercury is one of the five typical planets visible to the human eye and is named after the fast-moving Roman messenger god. The planet’s actual discovery date is unknown, although astronomers Galileo Galilei and Thomas Harriot first viewed it using telescopes in the 17th century. Mercury is the least investigated terrestrial planet, with only two spacecraft having visited it thus far, both robotic and NASA-launched. Mariner 10 was launched in 1973 and scanned approximately 45% of the planet’s surface between 1974 and March 1975, when the mission ended.
MESSENGER was launched in 2004 and became the first spacecraft to orbit Mercury in 2011. This mission lasted four years, until the probe succumbed to the planet’s gravity and crashed into its surface in 2015. It gathered a large amount of data and photos and relayed them back to Earth for scientific analysis.
ATMOSPHERE OF MERCURY
Among all of the planets in our solar system Mercury has the thinnest atmosphere, even thinner than Mars. Compared to the tense atmospheres of Earth and other planets, Mercury’s atmosphere is extremely thinner, which sometimes referred to as an exosphere. The exosphere is so barely populated that particle collisions between its constituents include oxygen, sodium, hydrogen, helium, and potassium. The atmospheric particles are largely derived from the interaction between the solar wind and the planet’s surface, as well as from the release of volatiles from cometary impacts and micrometeorites. The dynamic character of the exosphere is due to the constant restoration and modification that occurs from these outside activities. As we know being the closest planet to the Sun, Mercury is constantly being hit by high energy solar particles that ionise and remove atoms from its surface, adding to the composition of the exosphere. Because there is no significant atmosphere, Mercury has very high and low temperatures. Due to the rapid surface heating caused by the absence of atmospheric insulation, daytime temperatures can reach as high as 430°C (800°F). On the other hand, because the planet loses heat to space quickly, night time temperature drop to roughly -180°C (-290°F). The planet’s enability to hold on to heat as a result a thin atmosphere is the cause of this striking contrast. Since there is no substantial atmosphere, there is no wind or whether, and there is no atmospheric pressure in the exosphere. Mercury’s exosphere is ephemeral, reflecting the severe conditions that have moulded it due to strong solar radiation and the absence of strong enough gravitational field to hold on to a thicker atmosphere.
EXPLORATION OR MISSION TO MERCURY
In terms of global space interests, Mercury exploration has a limited significance. It is the least explored inner planet. As of now, only the Mariner 10 and MESSENGER missions had conducted close observations of Mercury. A third mission to Mercury, BepiColombo, which is a joint mission between the Japan Aerospace Exploration Agency (JAXA) and the European Space Agency, is to include two probes. The BepiColombo mission was approved in November 2009 and launched successfully on October 20, 2018. It is expected to reach orbit around Mercury in December 2025. Its primary mission will end in May 2027, with a possible extension to May 2028.
Past Missions
- Mariner 10: A probe by NASA whose primary objective was to observe the atmosphere, surface, and physical characteristics of Mercury and Venus.
- MESSENGER: MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) was a NASA orbital mission for Mercury. It launched from Cape Canaveral on August 3, 2004, following a one-day delay due to inclement weather.
Ongoing Mission
BepiColombo: This mission to Mercury will contain two satellites: the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO). Each orbiter has a separate purpose: the MPO acquires photos at various wavelengths to map Mercury’s surface and exosphere composition, while Mio studies the magnetosphere.
Future Missions
- Mercury-P
- Mercury Lander
- Mercury Observer
POTENTIAL FOR LIFE
Mercury, the closest planet to the Sun, is an improbable candidate for life as we know it. The planet’s severe environment poses numerous serious obstacles. Mercury’s surface temperatures range from roughly 430°C (800°F) in the day to -180°C (-290°F) at night, leading in significant temperature variations due to its thin atmosphere, which cannot hold heat. Mercury also lacks liquid water, which is an essential component for sustaining the life. The intense solar radiation and absence of a magnetic field further expose the planet’s surface to harmful solar winds, which makes it even more inhabitable. While the likelihood of life on Mercury is extremely distant. Some experts believe that microbial life might last in the perpetually shaded craters in the poles, where ice deposits have been discovered. However, even these locations are likely to be too severe for life as we know it.
CONCLUSION
The smallest planet in our solar system, provides an intriguing peek into the extremes of planetary environments. Mercury’s close proximity to the Sun causes extreme temperature variations, burning during the day and freezing at night. Its abandoned cratered surface, similar to our Moon, tells the narrative of a world sculpted by impacts and a lack of atmosphere to shield it from the Sun’s harsh radiation. Despite its size, Mercury has the second-densest iron core, indicating a distinct geological past. Mercury, being the innermost planet, reminds us of our solar system’s dynamic and diverse nature.
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