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> Other than its impressive size for a near-Earth asteroid, little was known about JO25. It was discovered in 2014 by the Catalina Sky Survey in Arizona, part of NASA and the University of Arizona's Near Earth Object (NEO) Observations Project, who were really only able to discern its size and orbit – and that it has a perplexingly reflective surface.

But as the asteroid approached Earth, we learned more about it. It has a "peanut"-esque shape. It's larger than previously estimated, with the size upped from 2,000 feet across to 3,280.

In addition to Slooh, NASA and the National Science Foundation announced their intentions to observe the mysterious asteroid with their radio telescopes. The Minor Planet Center has designated JO25 as a Potentially Hazardous Asteroid, as all space rocks at least one kilometer (0.6 miles) across that come within 4.3 million miles of Earth are.

It also means that there's a non-zero chance of it striking Earth one day – although that chance is still extremely low. Even if JO25 slams into Earth on its next close approach, that won't be until the 26th century or so.

"Although there is no possibility for the asteroid to collide with our planet, this will be a very close approach for an asteroid this size," NASA said in a statement. "Astronomers plan to observe it with telescopes around the world to learn as much about it as possible."

JO25 is the largest asteroid to make a close approach to Earth in 13 years. The last asteroid to outsize it was the 3.1-mile Toutatis, which in 2004 came even closer to Earth than JO25 did.

In August 2027, the asteroid 1999 AN10 will come within 250,000 miles of Earth. AN10 is slightly smaller than JO25 at 2,600 feet across, and will at one point be closer to our planet than the Moon is. </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> 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> SAN FRANCISCO (CBS SF) – A giant asteroid measuring about 2,000 feet across is passing by the Earth at a safe distance on Wednesday, according to NASA.

The asteroid, known as “2014 JO25” is safely passing by our planet at a distance of about 1.1 million miles. By comparison, the moon is 238,000 miles away, 4.6 times closer.

After Wednesday’s flyby, stargazers may be able to see the asteroid with a small telescope for the next 1-2 nights.

While small asteroids pass by within that distance each week, NASA said this is the first time an asteroid so large has passed this close in more than a decade. In 2004 asteroid Toutatis, which is about 3 miles wide, whizzed by Earth from four lunar distances away.

In 2027, an even larger asteroid is expected to pass significantly close to Earth. Asteroid “1999 AN10,” which is half a mile wide, will pass by about 236,000 miles from Earth, NASA said.

The last time asteroid 2014 JO25 passed this close to Earth was at least 400 years ago. It is not expected to pass this close to Earth for at least the next 500 years. </s> A mountain-size space rock cruised past Earth this morning (Sept. 1) in a record-breaking encounter that has long had scientists drooling.

At 8:06 a.m. EDT (1206 GMT) today, the roughly 2.7-mile-wide (4.4 kilometers) asteroid 3122 Florence came within a mere 4.4 million miles (7 million km) of Earth — just 18 times the distance from our planet to the moon.

"Nothing this big has passed this close to Earth since we've been tracking," Paul Chodas, manager of the Center for Near-Earth Object Studies at NASA's Jet Propulsion Laboratory in Pasadena, California, told Space.com. "This is a once-in-40-year-event kind of thing." [Famous Asteroid Rock Flybys and Close Calls (Infographic)]

The big asteroid 3122 Florence, as seen by the Virtual Telescope Project on Aug. 30, 2017 — two days before its closest approach to Earth. (Image credit: Gianluca Masi/Virtual Telescope Project)

Only 10 or so asteroids as big as Florence exist in near-Earth space, Chodas said. There was never any chance of the space rock hitting us on this encounter, and astronomers have mapped out Florence's orbit well enough to know that it poses no threat to Earth for the next few centuries at least, he stressed. (But if something as big as Florence did hit us, it would be very bad: Scientists regard any impactor at least 0.6 miles, or 1 km, across as a potential civilization-ender.)

Florence was discovered by astronomer Schelte "Bobby" Bus in 1981 at Australia's Siding Spring Observatory. The space rock loops around the sun every 2.35 years on an elliptical path, getting as close to our star as 1 astronomical unit (AU) and as far away as 2.5 AU. (One AU is the average Earth-sun distance — about 93 million miles, or 150 million km.)

Astronomers have also determined that Florence is a superfast spinner, completing one rotation every 2.4 hours.

"If it were spinning any faster, it would fly apart," Chodas said. "What often happens is, asteroids that are spinning this quickly rearrange into the shape of a top, where they have kind of a bulge at the equator."

But that's just an inference in Florence's case; the asteroid's shape isn't known for certain. Indeed, not much about Florence is. For example, astronomers don't know if the space rock has a moon. And the 2.7-mile size estimate, which is based on infrared observations by NASA's Spitzer Space Telescope and NEOWISE mission, is just that — an estimate. It could change once researchers get some better observations, Chodas said.

"There's a lot to learn about this little world," he said.

On Sept. 1, asteroid Florence will fly by Earth, and come to within about 18 times the distance from the Earth to the moon. (Image credit: NASA)

Which brings us back to today's flyby. Florence has come close enough on this encounter — eight times closer to Earth than it's ever been since its 1981 discovery, Chodas said — to be pinged by radar, and scientists are taking full advantage of the opportunity. They've been using powerful facilities such as NASA's Goldstone Solar System Radar in California and the Arecibo Observatory in Puerto Rico to get the first-ever good looks at Florence.

The radar images should reveal Florence's true size and shape. They may even achieve 10-foot (3 meters) resolution, allowing surface features such as boulders and craters to be spotted, Chodas said. Optical telescopes around the world have been trained on Florence as well, gathering other types of data that will further flesh out researchers' understanding of the asteroid, he added. [In Photos: Potentially Dangerous Asteroids]

This flyby is like a space mission to an asteroid, "but the asteroid is coming to us," Chodas said.

This sky map by Sky & Telescope magazine shows the location of the asteroid 3122 Florence as it moves across the night sky in late August and early September 2017. The asteroid will fly within 4.4 million miles (7.1 million km) of Earth on Sept. 1. (Image credit: Sky & Telescope Magazine diagram)

Astronomers aren't the only ones who can get looks at Florence right now; the asteroid should be visible through backyard telescopes for the next few days. You can read about how to see asteroid Florence in telescopes here.

Editor's Note: If you capture a great image of asteroid Florence moving across the sky and would like to share it with Space.com and our news partners, send photos and comments to spacephotos@space.com.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com. </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 </s> A 2,000-foot wide asteroid is passing by the Earth on Wednesday at a distance of of 1.1 million miles, making it one of closet approaches by an asteroid of this size in this decade.

The asteroid, 2014 JO25, will be about 4 times the distance of the moon as it makes it closest approach to Earth. The asteroid poses no risk to the Earth, NASA said.

NASA said that the asteroid will be visible with a small telescope Wednesday and Thursday nights.

According to NASA, 2014 JO25 is the closest an asteroid of its size will come to the Earth until 2027, when the half-mile-wide asteroid 1999 AN10 will fly by at just 225,000 miles away from the Earth.

2014 JO25 is on a path from the outer reaches of the solar system, past Earth's orbit. It will continue to pass by the Earth, but not coming close to the Earth again for another 500 years.
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.