While similarly-sized planets have been found before, the latest one, known as Kepler-4-5-2-b, is circling a star that is very similar to, but older than the sun at a distance about the same as Earth's orbit.
The star is estimated to be 1.2 billion years older than the sun.
It's one of 12 new planets United States scientists say lie beyond the solar system.
A NASA spokesman, John Grunsfeld says it is a major development in space exploration.
"We are announcing the discovery of an Exoplanet that as far as we can tell is a pretty good, close cousin to the earth and our sun. This is about the closest so far, and I really emphasise the so far because the Kepler data set is very rich and the science community has full access to be able to extract future discoveries out of the data set".
The discovery was made through NASA's Kepler telescope.
Kepler was launched by NASA to discover Earth-like planets orbiting other stars in 2009.
It was named after German Renaissance astronomer Johannes Kepler.
Based on its size, scientists believe Kepler-4-5-2-b is rocky and Earth-like and positioned at the right distance for liquid surface water, which is believed to be necessary for life.
Kepler Data analyst at Nasa's Research Centre Jon Jenkins explains what is known about the planet.
"Now this illustration draws upon the facts that we do know about this planet and its star. The star is the same surface temperature and type as the sun, a G2 star. The star is ten per cent bigger and twenty brighter than our sun as it's somewhat older and this planet orbits its star every 385 days and is just five per cent farther than from it's star than the earth."
Mr Jenkins believes six billion years is enough time and opportunity for life to arise somewhere on its surface or in its oceans should all the necessary ingredients and conditions needed for life exist on the planet.
Regardless of whether life is possible there, Mr Jenkins says it's simply awe-inspiring to consider that this planet has spent six billion years in the habitable zone of its star, acting as a new neighbour for planet Earth.
"Today the earth is a little less lonely because there is a new kid on the block who moved in just right next door, in terms of the surface temperature of the star it orbits and the energy it receives from the star."
As for life on the planet, scientists say current technology doesn't allow us to see.
But NASA Astrophysicist Marc Kuchner says as stars age they get hotter, which could be trigger a greenhouse effect on the surface, which could render them uninhabitable.
"The number of planets that are really in the range of earth's size and really in their habitable zones is tiny and these are precious and this really a major discovery.
Scientists have previously found earth-sized planets orbiting in stars' so-called "habitable zones," but those stars are cooler and smaller than the sun.
With the discovery of Kepler-452b, the telescope has found 1,030 confirmed planets and identified about 4,700 candidate planets.
The list of potential planets includes 11 other near-Earth twins, nine of which circle sun-like stars.
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