Question

Which planet is the smallest in size in the Solar System?
a) Mercury
b) Venus
c) Mars
d) Saturn

Answer 1

Hint: Just like our Solar System, there are numerous other planetary systems present in the universe. Unlike our Milky Way galaxy, there are many other galaxies where the largest planets orbit closer to the sun.

Complete answer:
To define any planet as smallest or largest, there are certain ways to look for, such as, it is mass i.e., the amount of matter it contains within, and second, its volume i.e., how much space it holds up. Considering both these parameters, the smallest planet in our Solar System is Mercury, which happens to be existing closest to the sun unlike many other galaxies present in the universe where the biggest planets were drawn to the gravitational force of the sun and hence, knocked out or absorbed the other planets in their way.
For the longest period of time, Pluto was considered to be the smallest planet in our Solar System. But as the technology evolved, Scientists have discovered worlds that are similar to Pluto and after discussions and meetings, the International Astronomical Union decided to call these worlds dwarf planets, and hence, we are left with eight planets in our Solar System.
Mercury, with a mean radius of $2440 km$ and $3.3010 \times 1023kg$ in weight, is nearly 0.38 times Earth in size. Apart from this, Mercury has a density of $5.427 g/cm^3$, which is $0.38$ times that of Earth. So, what it means is that your weight on Mercury is $38\%$ of what your weight is on Earth. Mercury is a terrestrial planet meaning that its core consists of metals and silicate minerals which are spread over the core, a silicate mantle, and crust. But unlike other planets, its oversized metallic core eats up about 75% of the entire planet with its molten core.
 Also, its surface looks very similar to our moon because of the presence of the Rocky Mountains and there is the presence of wrinkles on its surface which is believed to have been caused by the intense pressures of the planet.

Therefore, the correct option is Option (A).

Note: The title of the “hottest” planet in our Solar System, despite its closeness to the sun, doesn’t go to Mercury because of its lack of atmosphere. On the other hand, Venus, because of the presence of a thick atmosphere, holds up most of the radiation coming from the sun and hence, the hottest planet in our Solar System.