A large asteroid that has its own tiny companion moon is set to whiz past Earth this weekend.

The so-called binary asteroid, known as 1999 KW4, will make its closest approach at 7:05 p.m. ET on May 25, when it will be roughly 3.2 million miles from Earth—a safe distance but relatively paltry in space terms, NBC News reported. For context, this figure is about 13.5 times the distance between the Earth and the moon.

According to NASA's Center for Near-Earth Object Studies, 1999 KW4 will speed past Earth at around 48,000 miles per hour. The main object, shaped like a spinning top with a pronounced ridge around its equator, is estimated to measure around 0.8 miles in diameter. The small moon, which orbits at a distance of 1.6 miles every 16 hours, is thought to be around the third of that size, EarthSky reported.

1999 KW4 was first discovered in 1999 by the Lincoln Near-Earth Asteroid Research program in New Mexico. Since then, it has been extensively tracked and studied by astronomers. In fact, the object will be closely watched during its latest close approach by scientists at various observatories as part of an international effort to protect Earth from future catastrophic asteroid strikes.

"It's one of the closest binary flybys probably in recent history," Vishnu Reddy, a planetary scientist at the University of Arizona in Tucson, told NBC News. "That's what makes it a very interesting target."

1999 KW4 has been classified as a Near Earth Object (NEO), a term that refers to any asteroid or comet whose orbit takes it within 121 million miles of the sun, as well as within approximately 30 million miles of Earth.

It has also been defined as a "potentially hazardous object," meaning any NEO that has a (typically small) chance of colliding with Earth—i.e., the predicted minimum approach distance is less than 4.6 million miles—and is greater than 460 feet in diameter.

According to EarthSky, 1999 KW4 is the largest space rock that will come this close to our planet until June 2027, when asteroid 4953 (1990 MU), which is estimated to measure at least 2.5 miles in diameter, will sail past the Earth.

Currently, researchers know of more than 18,000 NEOs, of which over 1,800 are considered potentially hazardous. While there are a handful of potentially hazardous objects that are predicted to have a small chance of colliding with Earth in tens to hundreds of years, the odds will likely fall as monitoring stations make more observations, enabling more accurate predictions of their trajectories. </s> NASA astronomers expect that an asteroid will flyby our planet this weekend. The space rock called the 1999 KW4 will swing by the Earth around 7:05 p.m. ET on Saturday and when it does it'll bring along its own moon as well.

"It's one of the closest binary flybys probably in recent history," planetary scientist Vishnu Reddy told NBC News. "That's what makes it a very interesting target."

The space rock is around 1.5 km wide which is around three times the size of its moon, which is around 0.5 km. At its closest, the asteroid will be more than 3 million miles away from our planet, so there's no point of worrying. The next approach that the 1999 KW4 will make with the Earth will be in 2036, so keep your stargazing equipment ready for the weekend.

Last week, a space rock hurtling at high speed of 21,500mph skimmed Earth at a fraction of the distance between our planet and the Moon, revealed NASA's asteroid trackers. The asteroid known as the Asteroid 2019 JH7, shot past our planet on May 16.

According to NASA, the asteroid shot extremely close to the Earth. The flyby happened just two days after NASA observed the asteroid heading towards our planet. NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, said the asteroid's trajectory falls under the "Earth Close Approach" category. </s> A 2,000-foot-long asteroid, almost twice the size of the Rose Bowl, will zip safely past Earth on Wednesday at a distance of about 1.1 million miles, about 4.6 times the distance from Earth to the moon.

Although there is no possibility the asteroid, with the ungainly name of 2014 JO25, could collide with our planet, it will be a very close approach for an asteroid of this size, NASA said.

“Close is kind of a relative term,” AccuWeather meteorologist Brian Lada said. “The closest it’s going to be to the Earth is more than a million miles away.”

It's the closest this asteroid has come to Earth for at least the past 400 years and will be its closest approach for at least the next 500 years.

NASA said the approach is the closest by any known asteroid of this size since the 3.1-mile-wide asteroid Toutatis approached within about four lunar distances in September 2004. Not until 2027 will we have another shot at seeing a big rock tumble so close by, Sky and Telescope said.



 The asteroid is so massive that astronomy website Slooh.com nicknamed it after popular movie star Dwayne Johnson, aka The Rock.

The flyby should also be visible with amateur telescopes, beginning in the early morning hours on Wednesday and then again that night, according to EarthSky.org. Wednesday morning, it can be spotted in the northern sky near the constellation of Draco.

Wednesday night, asteroid 2014 JO25 will pass though the constellations Canes Venatici and Coma Berenices in the eastern sky.

The asteroid was discovered in May 2014 by astronomers at the Catalina Sky Survey near Tucson, Ariz. </s> A fast-moving asteroid will make a close flyby of Earth this Super Bowl Sunday (Feb. 4), but it poses no risk of hitting our planet, according to NASA.

The asteroid, called 2002 AJ129, will make its closest approach to Earth at 4:30 p.m. EST (2130 GMT), and will be about 2.6 million miles (4.2 million kilometers) from our planet at its closest point, NASA officials said. It's traveling at a breathtaking speed of about 76,000 mph (122,310 km/h), faster than most near-Earth asteroids, they added.

But while asteroid 2002 AJ129 is classified as "potentially hazardous" by NASA, at no point now or during the next century does it pose an impact threat to Earth, NASA officials said. Asteroids are classified potentially hazardous if they are larger than 460 feet (140 meters) in diameter and are in orbits that approach within 4.65 million miles (7.48 million km) of Earth. [In Images: Potentially Dangerous Asteroids Tracked by NASA]

"We have been tracking this asteroid for over 14 years and know its orbit very accurately," Paul Chodas, manager of NASA's Center for Near-Earth Object Studies at the Jet Propulsion Laboratory, Pasadena, California, said in the statement. "Our calculations indicate that asteroid 2002 AJ129 has no chance — zero — of colliding with Earth on Feb. 4 or any time over the next 100 years."

Asteroid 2002 AJ129 will make its closest approach to Earth on Feb. 4, 2018, at 4:30 p.m. EST (2130 GMT). At closest approach, the asteroid will be no closer than 10 times the distance between Earth and the moon. (Image credit: NASA/JPL-Caltech)

The space rock will be no closer than about 10 times the distance between the Earth and moon. (The average distance between the Earth and moon is about 238,855 miles, or about 384,400 km.)

Asteroid 2002 AJ129 is a mid-size asteroid that is somewhere between 0.3 miles and 0.75 miles (0.5 to 1.2 kilometers) across. It was discovered on Jan. 15, 2002 by astronomers with a then-NASA-sponsored Near Earth Asteroid Tracking project at the Maui Space Surveillance Site on Haleakala, Hawaii.

The asteroid's unusually fast speed was likely caused by a its orbit, which brings 2002 AJ129 extremely close to the sun, whipping around the star at a range of 11 million miles (18 million km), NASA officials said.

You can see live views of asteroid 2002 AJ129 today here at the Virtual Telescope Project website here at 6 p.m. EST (2300 GMT).

Email Tariq Malik at tmalik@space.com or follow him @tariqjmalik and Google+. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com. </s> Grab your telescope and get ready – an asteroid will make a very close approach to the Earth Wednesday.

In astronomical terms, peanut-shaped 2014 JO25 will fly within 4.6 lunar distances of the Earth. Since the distance from the Earth to the Moon is approximately 236,000 miles, this means 2014 JO25 will miss the earth by a margin of 1.1 million miles.

Right next door, really, when you think of the vast universal distances.

The asteroid is approximately 2,000 feet in size. It’s the closest an asteroid of any size has come to the Earth since 3.1 mile wide Asteroid Toutatis waved hello in September 2004 on its way by.

Asteroid 2014 JO25 will be visible starting Wednesday in the night sky in small optical telescopes for one or two nights. Its surface is twice as reflective as the moon, and should brighten to magnitude 11.

Brightness of stars is assigned a number starting with the brightest star at about -1 magnitude. Dimmer stars are zero or positive numbers. The larger the number means the dimmer the star is. A star -1 magnitude is brighter than a star 0 magnitude.

Watch the video animation from NASA showing the flyby in the video player above

The asteroid was discovered in May 2014 by astronomers at the Catalina Sky Survey near Tucson, Arizona — a project of NASA’s NEO Observations Program in collaboration with the University of Arizona.

Small asteroids pass within this distance of Earth several times each week, so there really is nothing to worry about.

The next known encounter of an asteroid of comparable size will occur in 2027 when the half-mile-wide asteroid 1999 AN10 will fly by at one lunar distance, about 236,000 miles (380,000 kilometers).

The encounter is providing an outstanding opportunity to study this asteroid, and astronomers plan to observe it with telescopes around the world to learn as much about it as possible.

Radar observations are planned at NASA’s Goldstone Solar System Radar in California and the National Science Foundation’s Arecibo Observatory in Puerto Rico. The resulting radar images could reveal surface details as small as a few meters.

This is the closest 2014 JO25 has come to Earth for about 400 years and will be its closest approach for at least the next 500 years.

Also on Wednesday, the comet PanSTARRS will have its closest approach to Earth, at a very safe distance of 109 million miles.

A faint fuzzball in the sky when it was discovered in 2015 by the Pan-STARRS survey team using a telescope on the summit of Haleakala, Hawaii, the comet has brightened considerably due to a recent outburst and is now visible in the dawn sky with binoculars or a small telescope. </s> A large asteroid is hurtling toward Earth -- but there's no need to duck and cover.

The space rock, known by the very dull name of 2014 JO25, will safely fly by Earth on April 19, according to NASA. The chances of it pounding our planet and leaving us for the dead? Zero, experts say.

"Although there is no possibility for the asteroid to collide with our planet, this will be a very close approach for an asteroid of this size," NASA said in a statement.

What size are we talking about? Measurements taken by NASA's NEOWISE space probe indicate the asteroid is about 2,000 feet (650 meters) in size. That's about 670 yards (613 meters), or about the length of six NFL football fields.

And how close is "very close"? NASA says this rock will come about 1.1 million miles (1.8 million kilometers) from Earth. That's about 4.6 times the distance from Earth to the moon. The moon, by the way, is about 239,000 miles (384,400 kilometers) from Earth.

While several small asteroids pass within this distance of Earth a few times a week, this is the closest by any known asteroid of this size or bigger in 13 years -- since asteroid Toutatis in 2004, according to the space agency.

Can you see asteroid 2014 JO25? Well, maybe. This asteroid has a reflective surface and you might be able to see it with a telescope.

"The asteroid will approach Earth from the direction of the sun and will become visible in the night sky after April 19," NASA said.

If you don't have your own telescope, you can watch the asteroid online.

Astronomers discovered 2014 J025 three years ago (you guessed it in 2014). This will be its closest encounter with Earth for the last 400 years. NASA said telescopes around the world will be trained on it during the flyby to try to learn more about it.

"Radar observations are planned at NASA's Goldstone Solar System Radar in California and the National Science Foundation's Arecibo Observatory in Puerto Rico, and the resulting radar images could reveal surface details as small as a few meters," NASA said.

If you head out to try to spot the asteroid, you might also want to check out comet PanSTARRS (C/2015 ER61). It also is making its closest approach to Earth -- coming about 109 million miles (175 million kilometers) from the planet. NASA said it's visible in the dawn sky with binoculars or a small telescope. </s> Asteroid 1981 ET3, also known as Florence, will skim past Earth on September 1 at a distance of seven million kilometres.

That is about 18 times the distance between the Earth and the moon and the closest this asteroid has been since 1890.

The next time such a space rock will fly this close is in 2050, according to Nasa.

At a staggering 4.8 kilometres wide – the largest that has ever been discovered since Nasa began tracking asteroids. </s> Asteroid 2002 AJ129, an intermediate-sized near-Earth asteroid will pass by Earth on Sunday, February 4, 2018.

The asteroid will make its closest approach to the Earth at a distance which is greater than 10 times the distance between Earth and the Moon. It is predicted to pass by at around 1:30 p.m. PST (4:30 p.m. EST/ 21:30 UTC).

The asteroid is believed to have a size between 0.3 miles or 0.5 kilometers and 0.75 miles or 1.2 kilometers.

However, Astronomers do not have any fears about the flyby. Paul Chodas, the manager of NASA's Center for Near-Earth Object Studies at the Jet Propulsion Laboratory, Pasadena, California, said, "We have been tracking this asteroid for over 14 years and know its orbit very accurately. Our calculations indicate that asteroid 2002 AJ129 has no chance-zero-of colliding with Earth on Feb.4 or anytime over the next 100 years."

The asteroid will have a velocity of 76,000 mph (34 kilometers per second) at its closest distance. This is higher than the majority of the near-Earth object during their flyby across Earth. The flyby velocity is higher due to the asteroid's orbit which approaches the sun at a distance of 11 million miles or 18 million kilometers.

It was discovered by NASA-sponsored Near Earth Asteroid Tracking project at the Maui Space Surveillance Site on Haleakala, Hawaii on January 15, 2002.

Even though asteroid 2002 AJ129 is categorized as a Potentially Hazardous Asteroid (PHA), it will not form any collision with Earth any soon. JPL's Center for Near-Earth Object Studies makes observations on the asteroids, comets or any other bodies which pass by Earth for the NASA's Near-Earth Object Observation Program.

NASA's Planetary Defense Coordination Office studies the near earth bodies to avoid any potential hazards or collisions with Earth. They also aim to work to tackle such situations warn people and lead any disaster management missions.

Space organizations are also keenly watching NEOs during their close encounters with Earth. One such observation has led to the identification of 'Oumuamua', the first interstellar object to pass through the Solar System near Earth. </s> The asteroid, dubbed by NASA Asteroid 2018 YQ2, is expected to approach our home planet just after midnight. NASA’s asteroid experts at the California-based Jet Propulsion Laboratory (JPL) predict YQ2 will flyby at 12.07am GMT (UTC) on Tuesday, January 8. During this flyby, the imposing asteroid will reach its closest possible distance to the planet – a so-called “Earth Close Approach”. The asteroid is not expected to hit the Earth anytime soon but tonight’s flyby will be the first of two incredibly close encounters this year.

NASA expects Asteroid YQ2 to visit the Earth again in eight months on the evening of August 26, 2019. And the asteroid’s impressive measurements are a good enough reason for NASA’s asteroid trackers to pay close attention to the space rock. NASA’s JPL scientists estimate YQ2 measures in the range of 52.5ft to 118.1ft (16m to 36m) in diameter. Any asteroid in this size range could pack enough force to cause injury and destruction upon atmospheric entry. READ MORE: Rogue asteroids could WIPE OUT life on Earth, warns Stephen Hawking

The 2013 Chelyabinsk meteor, which is estimated to have measured around 65.6ft (20m), injured more than 1,000 people in Russia when it exploded over Chelyabinsk. At the upper end of YQ2’s estimate, the space rock is about more than twice as tall as the Hollywood Sign in Los Angeles, is six-times as tall as an average giraffe and is nine-times longer than a Volkswagen Beatle. Thankfully, even at its closest, Asteroid YQ2 will miss the Earth completely by nearly two million miles. NASA believes the space rock will reach 0.01919 astronomical units (au) from the Earth – enough to dub it a “Near-Earth Object” (NEO) but not close enough to sound the alarm bells. READ MORE: Black hole in the middle of Milky Way could grow TENFOLD

One astronomical unit is the distance from Earth to the Sun and equals about 93 million miles (149.6 million km). Asteroid YQ2 will considerably cut this distance down tonight to just 1.78 million miles (2.87 million km).

This is roughly the equivalent of 7.47 Lunar Distances (LD) or 7.47-times the distance from Earth to the Moon. And the space rock will dash through space at breakneck speeds of more than 12,000mph or 5.68km per second. As they barrel through the solar system, NEOs like Asteroid YQ2 sometimes come close enough to our home world to spark interest from NASA. READ MORE: Was Einstein WRONG? Scientists probe supermassive BLACK HOLE to disprove theory of gravity
Binary Aten asteroid (66391) 1999 KW4 and its minor-planet moon make their closest-ever recorded flyby of Earth at 3.2 million miles away. The asteroid will approach even closer at 0.0155 AU (2,320,000 km) from Earth in 2036, and is the largest asteroid to approach Earth until (4953) 1990 MU in June 2027.