4 According to some estimates, rainforests and other terrestrial plants produce only 30% of the Earth’s free oxygen. The remaining 70% is produced mainly by phytoplankton in marine environments.

We have always thought that the plants on land are largely responsible for producing the oxygen we breathe in this world. Rarely do we hear people discussing the role of marine plants in oxygen production. Free oxygen is produced by the light-driven splitting of water during oxygenic photosynthesis. There are several estimates about the role of plants in marine environments in producing free oxygen on Earth.

One estimate states that phytoplanktons like green algae, cyanobacteria etc. produce 70% of the free oxygen. That leaves the terrestrial plants producing only 30%. Some estimates state that it is higher than 70%, while other estimates say it is lower. Those that think it is lower only put the contribution of marine plants at around 45%. (source)

5. The largest known bony fish in the world, the ocean sunfish, weighs about two tons and feasts on jellyfish. The female can produce about 300,000,000 eggs at a time.

Weighing generally between 247-1,000 kilograms, the ocean sunfish is found in tropical and temperate waters around the globe. A sunfish that was caught in 1910 weighed about 1,600 kilograms. About 15% of the sunfish’s diet consists of jellyfish and salps. They also consume small fishes, crustaceans, fish larvae, and squid. The silvery grey or sometimes white sunfish can have a fin-to-fin length of about 8.2 feet. They are laterally flat and have a tail-like structure at the back.

The reproductive habits of the ocean sunfish are not well-known except for a few facts like they produce about 300 million eggs at a time which is more than any known vertebrate. The eggs are externally fertilized by sperm after being released into the water. The ocean sunfish grows really quickly, growing millions of times its original size at birth. Sea lions, sharks, and killer whales prey on these fishes. They cannot survive for long in captivity, and their average lifespan in the oceans has not determined yet. (source)

6 A solar day on the planet Mercury is longer than its year.

Mercury, the closest known planet to the Sun in the solar system, is a planet of extremes. Its days and nights are extremely long compared to the days and nights on Earth. To complete one orbit around the Sun, Mercury takes 88 (87.969 to be precise) Earth days. That means that a year on Mercury is about 88 Earth days. However, to complete one rotation around its axis, the planet takes 58. 646 Earth days, which is one sidereal day.

This means that the planet has a spin-orbit resonance of 3:2. That means the planet makes three rotations for two orbits. The Sun does not return to the same place in 24 hours, like the Earth. It takes 176 Earth days for the Sun to set, rise, and come back to the same place in Mercury’s sky because of the spin-orbit resonance. So technically, one solar day on Mercury is equal to 176 Earth solar days.

Mercury, when at its closest during its orbit around the sun, is at a distance of about 46 million kilometers, closer than any other known planet. Its farthest distance from the Sun during its orbit is about 70 million kilometers. Its average orbital velocity is 47.362 kilometers per second. (source)