Twin asteroids passing by earth

An asteroid with a moon, or a binary asteroid, will pass by Earth tonight NZ time (1105 GMT). This wlil be it’s fourth flyby since it was discovered in in 1999, but it will be quite distant at it’s closest – more than 12 times more distant than our own Moon. An Asteroid with Its Own Moon Will Zip Past Earth Tonight

A very big asteroid with its own little moon is going to zip past Earth tonight (May 25) — close enough that, with some preparation and a decent telescope, amateur astronomers may spot it blotting out the stars.

This moon-and-asteroid system, called 1999 KW4, is made up of two rocks. The big one is about 0.8 miles (1.3 kilometers) wide, according to NASA, and shaped like a spinning top. The smaller one is more elongated and stretches 0.35 miles (0.57 km) along its longest dimension. It points lengthwise toward its much larger twin.

Together, the asteroid and its minimoon will pass Earth at such a strange, steep angle that NASA called them “the least accessible … for a spacecraft mission of any known binary near-Earth asteroid.”

The two asteroids will pass closest to Earth at 7:05 pm EDT (1105 GMT), when they’ll be just 3,219,955 miles (5,182,015 km) from the planet’s surface. That’s more than a dozen times the distance between the Earth and the moon in its orbit around our planet, and much too far for the space rocks to pose any threat. In fact, this is the fourth approach the binary asteroids have made toward Earth since they were discovered in 1999, and not the closest.

“1999 KW4 approaches within 0.05 AU of Earth several times each century,” NASA’s report on the object said. “This trend exists from at least [the year] 1600 [to] 2500.”

“AU” refers to “astronomical units,” a unit equal to the distance between Earth and the sun. So 0.05 AU is equal to one-twentieth the distance between Earth and sun, or about 4,650,000 miles (7,480,000 km). The two asteroids have passed even closer to Earth, without incident.

Bits of rock and ice are zinging around us all the time. The only difference is we are able to detect them now. Or at least some of them.

EarthSky reported that during the space rocks’ closest approach, they’ll be most visible in the Southern Hemisphere, appearing as fast-moving shadows against stars in the constellation Puppis. The two asteroids will remain visible for several days.

Visible for those with good enough telescopes and who know where to look – and have clear skies at night.

I haven’t heard of the Puppis Constellation. It appears to be close to the southern horizon at this time of year near Carina and Vela, lower in the southern sky than the Crux (Southern Cross).

puppis constellation,puppis stars,puppis location,puppis star map


Diamond shaped asteroid one of 29k+ NEO’s detected

Japan’s space agency is preparing to attempt two landings on a diamond shaped asteroid called Ryugu. It is one of over 18,000 Near Earth objects that have now been detected.

Image result for ryugu asteroid

900 metre wide Ryugu asteroid

Ryugu has been described as ‘unusually shaped’ but I think it has become obvious that asteroids are a wide variety of seemingly random shapes, so no particular shape should be seen as unusual. It would be very unusual if they all looked similar,

Ryugu is a C-type asteroid. Asteroids (NASA):

C-type (carbonaceous): Includes more than 75 percent of known asteroids. Very dark with an albedo of 0.03-0.09.
Composition is thought to be similar to the Sun, depleted in hydrogen, helium, and other volatiles. C-type asteroids inhabit the main belt’s outer regions.

S-type (silicaceous): Accounts for about 17 percent of known asteroids. Relatively bright with an albedo of 0.10-0.22. Composition is metallic iron mixed with iron- and magnesium-silicates. S-type asteroids dominate the inner asteroid belt.

M-type (metallic): Includes many of the rest of the known asteroids. Relatively bright with an albedo of 0.10-0.18. Composition is apparently dominated by metallic iron. M-type asteroids inhabit the main belt’s middle region.


Japan’s space agency will attempt to land a robotic unmanned landing craft on the surface of an asteroid 300 million-kilometers (186.4 million-miles) away from Earth next month.

The Hayabusa-2 spacecraft is currently orbiting around the diamond-shaped asteroid Ryugu, which it reached in June after a three-and-a-half year journey.

On September 21, the spacecraft will deploy the first of two landers onto the asteroid itself, where they will gather samples and conduct experiments. A second lander will be launched on October 3.

Later in the mission, the spacecraft itself will land on the asteroid after blowing a small crater in it using explosives, so samples can be gathered from below the object’s surface which have not been exposed to space.

JASA’s Asteroid Explorer “Hayabusa2” descended from its orbiting position (at a 20km altitude from Ryugu) to a minimum altitude of 851 m, on 6 -7 August 2018.

NASA has detected more than 29,000 Near Earth Objects, most over the last ten years, so the number is likely to keep increasing.


Near-Earth Objects (NEOs) are comets and asteroids that have been nudged by the gravitational attraction of nearby planets into orbits that allow them to enter the Earth’s neighborhood. Composed mostly of water ice with embedded dust particles, comets originally formed in the cold outer planetary system while most of the rocky asteroids formed in the warmer inner solar system between the orbits of Mars and Jupiter.

On a daily basis, about one hundred tons of interplanetary material drifts down to the Earth’s surface. Most of the smallest interplanetary particles that reach the Earth’s surface are the tiny dust particles that are released by comets as their ices vaporize in the solar neighborhood.

With an average interval of about 10,000 years, rocky or iron asteroids larger than about 100 meters would be expected to reach the Earth’s surface and cause local disasters or produce the tidal waves that can inundate low lying coastal areas. On an average of every several hundred thousand years or so, asteroids larger than a kilometer could cause global disasters.

No one should be overly concerned about an Earth impact of an asteroid or comet. The threat to any one person from auto accidents, disease, other natural disasters and a variety of other problems is much higher than the threat from NEOs. Over long periods of time, however, the chances of the Earth being impacted are not negligible so that some form of NEO insurance is warranted.

Around what?

NASA discovered that there was a satellite rock orbiting the asteroid that passed close by Earth earlier this week.

NASA has discovered a tiny moon 70 meters (230 feet) in diameter circling the asteroid that passed very close to Earth earlier this week, a situation that occurs in just 16 percent of the cases of known asteroids.

The tiny moon is orbiting the asteroid, which itself is only 325 meters (about 1,060 feet) in diameter.

If this asteroid went close enough to the moon it could get trapped into orbit.

Then there would be a moon around a moon around the Moon.

Around Earth. Around the Sun. Around the Milky Way. Around the Universe.

Around what?

Asteroid 2004 BL86

An asteroid is zipping past us over the next day or so,

It is estiamted be about 0.5 to 1 kilometre in diameter and is predicted to pass the Earth at a distance of 1.2 million kilometres – about three times the distance from the Earth to the moon.

NASA: Updated Charts for Asteroid 2004 BL86 Earth Flyby on Jan 26, 2015

To see 2004 BL86 NASA’s advice is to use a telescope or a decent pair of binoculars.

On its closest approach the best viewing will be done from the northern hemisphere. For the southern hemisphere, it will be quite a bit fainter, but still possible to spot.

An Australian guide (I can’t find a New Zealand guide):

After sunset on January 26, at about 9pm, 2004 BL86 will be visible towards the east, near the constellation Hydra. At this point it will only be at visual magnitude 10.4. It will look like a very pale star.

Simon O’Toole, a research astronomer at the Australian Astronomical Observatory, says it will be moving quite slowly across the sky.

“When you do observe it, it’s moving at about 1 degree per hour across the sky. That’s about the width of the moon every 30 minutes or so,” he says.

Throughout the evening it will track across the galactic plane and will still be viewable in the early hours of the next morning towards the north-west.

“For the really super keen who are still partying, at about 6am, it will be near the horizon, near the constellation Leo,” says Alan Duffy, a research fellow and astrophysicist at Swinburne University.

At this time of the morning, it will also be near Jupiter, one of the brightest objects in the night sky.

At around 6am the following morning, the asteroid can be found near the very bright planet Jupiter

Convert to New Zealand times but Aussie may be close enough.

Online: Virtual Telescope will be tracking the asteroid’s approach.