At a Glance

The asteroid will remain visible to the naked eye until July 16. But the peak viewing window ends Friday. It is the second most-massive body in the asteroid belt between Jupiter and Mars.

Vesta, a 326-mile-wide asteroid with an impressive 13-mile-high mountain, is now visible to the naked eye and will remain so until July 16. However, the peak viewing windowends Friday.

Vesta, thein the asteroid belt lbetween Jupiter and Mars, is making its closest swing by Earth in nearly two decades, according to Space.com. Only the asteroid Ceres surpasses Vesta in mass.

The asteroid came within on Tuesdayand is now beginning to grow dimmer, but it will remain visible for a few more weeks.

Vesta is unique because it possesses a 13-mile-high mountain at its south pole, one of the tallest known mountains in the universe. It is also one of the brightest. Covered with a crust of basaltic rock that is highly reflective, it casts back43 percent of the light that hits it. In comparison, the moon casts only12 percent of the light that strikes its surface.

Vesta is also the only remainingprotoplanetor surviving remnantof the earliest planetary building blocks in the solar system.

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To locate Vesta in the southeastern sky,Bob King of Sky and Telescopesays to " then star-hop with the naked eye or binoculars to 3.8-magnitude Mu (μ) Sagittarii. The asteroid is located 2.5°–4° northwest of that star through mid-June."

King notes that Vesta should be easy to spot because ithas "little competition from similarly bright stars."

The best way to observe any heavenly body is to get as far away from light as possible. The asteroidis said to give off a yellowish hue in the night sky. It will be better viewed through or a telescope, Mother Nature Network notes.

People inthe Southwest and in New England will have the best opportunity to take advantage of the asteroid's peak viewing windowtonight, said weather.com meteorologist Linda Lam.

On Fridaynight, the best chance for clear skies will be found from central Texas to California,she added.

Vesta won't come this close to Earth again until 2040.