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


Moon eclipse at sunrise Saturday

Tomorrow morning if the skies are clear we will be able to see the start of a full eclipse of the Moon as it sets in the west. The further south and further west, the more of it you will be able to see.

In the far south if conditions are right it will be possible to see the full eclipse in the west and the Sun rising in the east at the same time, a fairly rare event. As Earth is directly between the Moon and the Sun this is only possible due to the refraction of light around Earth’s atmosphere.

RNZ: Kiwis to get glimpse of blood moon

New Zealand will get a short glimpse at the longest lunar eclipse of the century on Saturday morning.

The blood moon will last for one hour and 43 minutes, just shy of the theoretical limit of a lunar eclipse which is one hour and 47 minutes.

Unfortunately, the eclipse will only be considered partial in New Zealand.

Stardome Observatory astronomy educator Josh Kirkley said New Zealanders wanting to see the blood moon should get a clear view of the western horizon and keep their eyes peeled from 6.25am until the moon sets at 7.20am.

He said the moon would begin to enter earth’s shadow (known as the penumbra) around 5.15am and would gradually dim until about 6.25am.

At that point, it would enter the part of shadow known as the umbra (darkest part of the shadow) and start to turn red.

The moon appears red (rather than in complete darkness) due to blue light from the earth’s atmosphere refracting sunlight onto the surface of the moon.

Mr Kirkley said that the sunrise would begin during the eclipse which would “wash out” the colours of the moon as it turned red.

However, he said it was still worth seeing as the next blood moon would not be visible in New Zealand until May 2021.

Newshub: Extremely rare ‘selenelion’ to be seen in South Island skies this weekend

The south of New Zealand will witness an extremely rare celestial event this weekend.

A few minutes after 8am on Saturday, South Islanders can observe a total lunar eclipse where the Sun and Moon are both visible, which is known as a ‘selenelion’.

The areas of our planet from which it can be experienced are very limited, because the total lunar eclipse must be on-going at the time of moonset/sunrise.

A selenelion happens when the eclipsed Moon can be seen on one horizon, whilst the rising Sun can also be observed near the opposite horizon, explains Dr Duncan Steel from the Centre for Space Science Technology in Otago.

This might seem impossible – as a typical lunar eclipse happens when the Sun, Earth and Moon are in a straight line – so if the Moon is above the horizon then the Sun must be below it.

But the selenelion is possible due to the bending of the rays of light caused by Earth’s atmosphere, says Dr Steel. This enables you to see both the eclipsed Moon and the Sun at the same time, so long as you’re in the right place.

The night skies have been great lately, with the moon nearing full, Mars more prominent than usual (at it’s closest for 17 years) not far from the Moon, Jupiter prominent high in the sky early and moving to set through the night, and Venus further west in the evening, bright for a while (it sets at 9:21 pm in Dunedin, earlier further north).

The sky has just cleared again in Dunedin, and Mars can be seen just to the right of the Moon.

The forecast is fairly mixed so I’ll have to wait until the morning to know whether the eclipse will be viewable or not.

Tour of the Moon

NASA has released a video tour of the Moon.

Take a virtual tour of the Moon in all-new 4K resolution, thanks to data provided by NASA’s Lunar Reconnaissance Orbiter spacecraft. As the visualization moves around the near side, far side, north and south poles, we highlight interesting features, sites, and information gathered on the lunar terrain.

This video is public domain and along with other supporting visualizations can be downloaded from the Scientific Visualization Studio at: Credit: NASA’s Goddard Space Flight Center/David Ladd

Music Provided By Killer Tracks: “Never Looking Back” – Frederick Wiedmann. “Flying over Turmoil” – Benjamin Krause & Scott Goodman.

Between the rings

A cool photo:

Not all of us. I’m not sure what side of Earth is facing Cassini there so I don’t know whether that view is of us, or of the other lot on the other side of our planet.

A closer look:

And zoomed in you can see the moon more easily:

More information about the Cassini mission:

‘Ingredients for life’ on Saturn moon

NASA reports: Ingredients for Life at Saturn’s Moon Enceladus

NASA’s Cassini spacecraft discovered hydrogen in the plume of gas and icy particles spraying from Saturn’s moon Enceladus.

The discovery means the small, icy moon — which has a global ocean under its surface — has a source of chemical energy that could be useful for microbes, if any exist there. The finding also provides further evidence that warm, mineral-laden water is pouring into the ocean from vents in the seafloor.

On Earth, such hydrothermal vents support thriving communities of life in complete isolation from sunlight.

Enceladus now appears likely to have all three of the ingredients scientists think life needs:

  • liquid water,
  • a source of energy (like sunlight or chemical energy),
  • and the right chemical ingredients (like carbon, hydrogen, nitrogen, oxygen).

Cassini is not able to detect life, and has found no evidence that Enceladus is inhabited. But if life is there, that means life is probably common throughout the cosmos; if life has not evolved there, it would suggest life is probably more complicated or unlikely than we have thought.

Either way the implications are profound.

Future missions to this icy moon may shed light on its habitability.

White smoker footage courtesy of: NOAA-OER / C.German (WHOI)

Saturn has 62 diverse moons (with confirmed orbits) so there is plenty of scope for a variety of conditions, including conditions including the ingredients of life.

Enceladus is the sixth largest moon of Saturn, about 500 kilometres in diameter (Earth’s Moon has a diameter of 3474 km).


Photo of Enceladus taken from Cassini

If life was able to become established and thrive on Earth then it’s logical to assume it could and will have happened elsewhere, but it’s cool to find evidence of where it could actually happen within our own solar system.

Some space stuff

Some cool space stuff.

Saturn’s moon Pan:  Here’s Our Best Look Yet at Saturn’s ‘UFO’ Moon


There’s a tiny “flying saucer” orbiting deep within Saturn’s rings, and a NASA probe has just gotten its most impressive look yet at the strange object.

The saucer is actually a little moon called Pan, and NASA’s Cassini spacecraft captured its distinctive shape on March 7 in a stunningly detailed series of images.

Named for the flute-playing Greek god of wild places, 21-mile-wide Pan is what’s called a shepherd moon. It lives within a gap in Saturn’s A ring, which is the farthest loop of icy particles from the planet.

“The shape, as others have also pointed out, is probably because it is always sweeping up fine dust from the rings,” Showalter explains. “The rings are very thin compared to the size of Pan, so the dust accumulates around its equator.”

Pan isn’t alone in its bizarre appearance: Another small moon, Atlas, bears a similar shape for similar reasons.

And on a different scale: Hubble Showcases a Remarkable Galactic Hybrid

A remarkable galactic hybrid

 This NASA/ESA Hubble Space Telescope image showcases the remarkable galaxy UGC 12591. UGC 12591 sits somewhere between a lenticular and a spiral. It lies just under 400 million light-years away from us in the westernmost region of the Pisces–Perseus Supercluster, a long chain of galaxy clusters that stretches out for hundreds of millions of light-years — one of the largest known structures in the cosmos.

The galaxy itself is also extraordinary: it is incredibly massive. The galaxy and its halo together contain several hundred billion times the mass of the sun; four times the mass of the Milky Way. It also whirls round extremely quickly, rotating at speeds of up to 1.8 million kilometers (1.1 million miles) per hour.

Observations with Hubble are helping astronomers to understand the mass of UGC 12591, and to determine whether the galaxy simply formed and grew slowly over time, or whether it might have grown unusually massive by colliding and merging with another large galaxy at some point in its past.

Image credit: ESA/Hubble & NASA

Text credit: European Space Agency



The moon we never see

Here’s a view of the moon we never see. Until now. From NASA:


…satellite images of the far side of the moon, illuminated by the sun, as it crosses between the DSCOVR spacecraft’s Earth Polychromatic Imaging Camera (EPIC) and telescope, and the Earth – one million miles away. Credits: NASA/NOAA
The dark side of the moon is facing us on Earth as the far side is in bright sunlight.

From a Million Miles Away, NASA Camera Shows Moon Crossing Face of Earth

A NASA camera aboard the Deep Space Climate Observatory (DSCOVR) satellite captured a unique view of the moon as it moved in front of the sunlit side of Earth last month. The series of test images shows the fully illuminated “dark side” of the moon that is never visible from Earth.

The images were captured by NASA’s Earth Polychromatic Imaging Camera (EPIC), a four megapixel CCD camera and telescope on the DSCOVR satellite orbiting 1 million miles from Earth. From its position between the sun and Earth, DSCOVR conducts its primary mission of real-time solar wind monitoring for the National Oceanic and Atmospheric Administration (NOAA).

And here’s the animation of images:

EPIC maintains a constant view of the fully illuminated Earth as it rotates, providing scientific observations of ozone, vegetation, cloud height and aerosols in the atmosphere. Once EPIC begins regular observations next month, the camera will provide a series of Earth images allowing study of daily variations over the entire globe. About twice a year the camera will capture the moon and Earth together as the orbit of DSCOVR crosses the orbital plane of the moon.

These images were taken between 3:50 p.m. and 8:45 p.m. EDT on July 16, showing the moon moving over the Pacific Ocean near North America.The North Pole is in the upper left corner of the image, reflecting the orbital tilt of Earth from the vantage point of the spacecraft.

The lunar far side lacks the large, dark, basaltic plains, or maria, that are so prominent on the Earth-facing side. The largest far side features are Mare Moscoviense in the upper left and Tsiolkovskiy crater in the lower left. A thin sliver of shadowed area of moon is visible on its right side.

“It is surprising how much brighter Earth is than the moon,” said Adam Szabo, DSCOVR project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Our planet is a truly brilliant object in dark space compared to the lunar surface.”

Once EPIC begins regular observations next month, NASA will post daily color images of Earth to a dedicated public website. These images, showing different views of the planet as it rotates through the day, will be available 12 to 36 hours after they are acquired.

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?

The other side

China’s Chang’e spacecraft has taken a photo of the Earth along with a view we don’t usually see, the other side of the moon.


EarthSky reported: Extraordinary shot of moon’s far side and Earth, from Chang’e

The Chinese Chang’e 5 test vehicle captured this extraordinary view of Earth over the far side of the moon on October 28, 2014. From Earth on this date, the phase of the moon was a waxing crescent. From the moon that day, the Earth was in a waning gibbous phase.

The Chinese Chang’e 5 spacecraft, which is testing lunar sample return technology, has rounded the lunar far side and is now on the return leg of its journey to the moon. It is landed back on Earth on Friday, October 31, 2014.

Moon Connection explains Why Do We Only See One Side of the Moon?

The same physical half of the Moon, the “near side”, is always facing Earth. That means there is a far side or so-called “dark side” that is never facing Earth and can only be seen from space. This is true regardless of the moon phase.

Why is this the case? We all know that the Earth rotates on its own axis, so theoretically, the Moon should also do the same, allowing us to get a full picture of the planetoid. Why are we limited to seeing only 50 percent? It turns out that the speed at which the Moon rotates has led to this particular phenomenon. Millions of years ago, the Moon spun at a much faster pace than it does now. However, the gravitational influence of the Earth has gradually acted upon the Moon to slow its rotation down, in the same way that the much smaller gravitational influence of the Moon acts upon the Earth to create tides. This influence slowed the rotational period of the Moon to match that of its orbit – about 29.5 days – and it is now “locked in” to this period.

If the Moon didn’t spin at all, then eventually it would show its far side to the Earth while moving around our planet in orbit. However, since the rotational period is exactly the same as the orbital period, the same portion of the Moon’s sphere is always facing the Earth.

We can actually see more than half the moon due to a ‘rocking’ motion.

Actually a little bit more than half of the Moon’s surface is observable from Earth. Since the Moon’s orbit is elliptical, and not circular, the speed of its orbital travel increases and decreases depending on how close it is to our planet. The rotational speed of the Moon is constant however – and this difference between orbital speed and rotational speed means that when the Moon is farthest from the Earth, its orbital speed slows down just enough to allow its rotational speed to overtake it, giving observers a small glimpse of the usually hidden area. The term for this “rocking” motion of the Moon is called libration and it allows for 59 percent of the Moon to be seen in total (over time).

There is no dark side of the moon, only a side we can’t see from Earth.

One reason that the far side of the Moon is frequently referred to as the “dark side” is because many people mistakenly think that it never sees any light from the Sun. In that sense the term “dark side” is wrong and misleading. In fact, since the Moon is constantly rotating on its own axis, there is no area of the planetoid which is in permanent darkness, and the far side of the Moon is only completely devoid of sunlight during a Full Moon – when the Sun is facing the Moon with the Earth in between.

What’s this got to do with politics? Nothing really, but I’ll make up an association.

There’s another side to most things, even though we may not find it easy to see it.