Mercury

                                                                       [1] Mercury

Being the closest and smallest planet to the sun, Mercury is approximately 4.503 billion years old and has the densest atmosphere out of all the planets within the solar system. It is so close to the sun actually that it "would appear more than three times as large as it does when viewed from Earth" [2] with an average distance of thirty six million miles from the surface of the planet to the Sun. Surprisingly, Mercury isn't the hottest planet within the solar system with its average temperature ranging between -180 degrees celcius to 430 degrees celcius due to the planet having little to no atmosphere to retain heat within its surface. Due to a slow rotation on its axis, one full rotation takes on average 59 Earth days to complete meaning one side of the planet is facing the sun for a much longer duration of time than the other side. Due to having a thin atmosphere mostly composed of hydrogen, oxygen, helium, potassium and sodium (caused by solar winds discussed in 'The Sun' blog), Mercury could therefore not sustain life. Another interesting feature of this planet is the various craters on its surface, more than any other planet in the solar system. [3]

[3] Mercury's Craters 

Due to a collision of numerous meteorites over a span of 4 billion years, 412 mercurian craters are known to live on Mercury's surface as of 2020. As seen in the picture above [3], the "relatively smooth plains between craters indicates that at one point the surface was probably volcanic, as lava flows filled in after the impacts of large objects" [4]. The 'Caloris Planitia', discovered in 1974 is the biggest crater  known to exist on Mercury's surface covering approximately 960 miles in diameter and is surrounded by approximately 1.2 miles of mountainous terrain called 'Caloris Montes'. NASA obtained images of this terrain during the 'Mariner 10' mission which launched in 1974 and took various images of the terrain on Mercurys surface. Overall Mercury, the smallest planet within the solar system has been able to prove beneficial to us here on Earth through proving Albert Einsteins theory of relatively that "space can 'curve' or to put it more accurately, it associates the force of gravity with the changing geometry of space-time" [5]. 

References

[1] pinterest.com. [2020]. Hubble Space Telescope Images. [Online] Available at: https://www.pinterest.com/pin/767089749013252025/ [Last Accessed 10/10/2020].

[2] solarsystem.nasa.gov. [2019]. Mercury. [Online] Available at: https://solarsystem.nasa.gov/planets/mercury/overview/ [Last Accessed 11/10/2020].

[3] nasa.gov. [2008]. MESSENGER. [Online] Available at: https://www.nasa.gov/mission_pages/messenger/multimedia/crater_count.html [Last accessed 11/10/2020].

[4] Russell, R. [2010]. Surface of Mercury. [Online] Available at: https://www.windows2universe.org/mercury/Interior_Surface/Surface/surface_overview.html [Last Accessed 11/10/2020]. 

[5] sciencealert.com. [n.d.]. What is The General Theory of Relativity?. [Online] Available at: https://www.sciencealert.com/general-relativity [Last Accessed 11/10/2020].