The imaginary extension of Earth's equator into space is called the celestial equator. It is an imaginary line in the sky above the Earth's equator, dividing the celestial sphere into northern and southern hemispheres.
The line of latitude found at 0 degrees is called the equator. It is an imaginary line that divides the Earth into the Northern and Southern Hemispheres.
That's a lot like asking "How was the top of this rock found ?" The equator is a definition. It's the location of all the points on Earth that are at equal distances from the north and south poles. Once somebody has defined the poles for you, you can find the points that are at equal distances from the poles, and if you find enough of them, bada-bing, the equator appears. Just like the equator, the top of the rock was there all the time, but nobody knew it. It needed somebody to come along and say "Let's find a place on the rock that's higher than any other place on the rock, and let's call that place the 'top' ." As soon as people agreed on what "top" means, they discovered the top.
your home
I call it the latitude of any point on the equator.
equator
No Canada is about 50 degrees of latitude north of the equator.
The jet stream.
the equator daaa
Zero latitude is the Equator.
Most modern civilized cultures with a sense of their place on Earth and/or any seafaring history refer to this imaginary line as the 'Prime Meridian'.
That's the Tropic of Capricorn, no matter what I call it.