Indira Gandhi Planetarium, Lucknow Veer Bahadur Singh Planetarium, Gorakhpur        Aryabhatt Planetarium, Rampur

Mercury

Mercury is the closest planet to the sun. Because of its closeness, its temperature in the daytime can reach up to (427 ℃). Since the planet has no atmosphere to retain that heat, so the nighttime temperature on the surface can drop to (-170 ℃).Mercury revolves around the sun in 88 days, traveling through space at nearly 31 miles (50 kms) per second faster than any other planet. The length of one Mercury day (sidereal rotation) is equal to 58.646 Earth days.

Internal Structure of Mercury:
• Mercury has a radius of 2439 km (1524 mi), and the metallic iron-nickel core is believed to make up about 75% of this distance.
• Mercury has no atmosphere and as a result, the surface is pocked by craters from collisions with asteroids over billions of years.

Atmospheric Composition of Mercury:

Components   CD(cm −2)   SD(cm−3)  
hydrogen   ~ 3 × 109   ~ 250  
molecular hydrogen   < 3 × 1015   < 1.4 × 107  
helium   < 3 × 1011   ~ 6 × 103  
atomic oxygen   < 3 × 1011   ~ 4 × 104  
molecular oxygen   < 9 × 1014   >< 2.5 × 107  
sodium   ~ 2 × 1011   1.7–3.8 × 104  
potassium   ~ 2 × 109   ~ 400  
calcium   ~ 1.1 × 108   ~ 300  
magnesium   ~ 4 × 1010   ~ 7.5 × 103  
argon   ~ 1.3 × 109   < 6.6 × 106  
water   < 1 × 1012   < 1.5 × 107  
NOTE: CD is column density & SD is surface density