Back غلاف عطارد الجوي Arabic Атмосфера на Меркурий Bulgarian Atmosféra Merkuru Czech Atmósfera de Mercurio Spanish جو عطارد Persian Atmosphère de Mercure French Merkurova atmosfera Croatian 水星の大気 Japanese 수성의 대기 Korean Атмосфера на Меркур Macedonian
 Mercury's surface, with the atmosphere too thin to be visible. | |
| General information | |
|---|---|
| Chemical species | Column density cm−2; Surface density cm−3[1] |
| Composition | |
| Hydrogen | ~ 3 × 109; ~ 250 |
| Molecular hydrogen | < 3 × 1015; < 1.4 × 107 |
| Helium | < 3 × 1011; ~ 6 × 103 |
| Oxygen | < 3 × 1011; ~ 4 × 104 |
| Molecular oxygen | < 9 × 1014; < 2.5 × 107 |
| Sodium | ~ 2 × 1011; 1.7–3.8 × 104 |
| Potassium | ~ 2 × 109; ~ 4000 |
| Calcium | ~ 1.1 × 108; ~ 3000 |
| Magnesium | ~ 4 × 1010; ~ 7.5 × 103 |
| Argon | ~ 1.3 × 109; < 6.6 × 106 |
| Water | < 1 × 1012; < 1.5 × 107 |
Mercury, being the closest to the Sun, with a weak magnetic field and the smallest mass of the recognized terrestrial planets, has a very tenuous and highly variable atmosphere (surface-bound exosphere) containing hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor, with a combined pressure level of about 10−14 bar (1 nPa).[2] The exospheric species originate either from the Solar wind or from the planetary crust. Solar light pushes the atmospheric gases away from the Sun, creating a comet-like tail behind the planet.
The existence of a Mercurian atmosphere was contentious until 1974, although by that time a consensus had formed that Mercury, like the Moon, lacked any substantial atmosphere. This conclusion was confirmed in 1974 when the unmanned Mariner 10 spaceprobe discovered only a tenuous exosphere. Later, in 2008, improved measurements were obtained by the MESSENGER spacecraft, which discovered magnesium in the Mercurian exosphere.
- ^ Killen 2007, p. 456, Table 5
- ^ "NASA—Mercury". Archived from the original on 2005-01-05. Retrieved 2009-09-26.