Earth is the only known planet that can sustain life. The current population is about 7.046 billion people.
Seasons
Earth has four seasons- Summer, Fall, Winter, and Spring. The cause of the seasons is the tilt of Earth's axis. They are NOT caused by the Earth moving closer or farther from the Sun.
The universe:
The most abundant element in the universe is Hydrogen, it makes up about 3/4 of the universe's mass.
The most abundant element in the universe is Hydrogen, it makes up about 3/4 of the universe's mass.