2017-8-14 : Asteroid to shave past Earth on Oct 12: ESA By Mariette Le Roux Paris

A house-sized asteroid will shave past our planet on October 12, far inside the Moon’s orbit but without posing any threat, astronomers said Thursday.  The space rock will zoom by harmlessly at a distance of about 44,000 kilometres (27,300 miles) — an eighth of the distance from the Earth to the Moon, according to the European Space Agency. This is just far enough to miss our geostationary satellites orbiting at about 36,000 kilometres.

“We know for sure that there is no possibility for this object to hit the Earth,” Detlef Koschny of ESA’s “Near Earth Objects” research team told AFP. There is no danger whatsoever.”

The asteroid, dubbed 2012 TC4, first flitted past our planet in October 2012 — at about double the distance — before disappearing from view.  It is about 15-30 metres (49-98 feet) long, and was travelling at a speed of some 14 kilometres (nine miles) per second when spotted.  Scientists expected the asteroid to return for a near-Earth rendezvous this year, but did not know how close it would get.  Now, the Very Large Telescope of the European Southern Observatory (ESO) in Chile has managed to track the rock down, some 56 million kilometres away, and determine its trajectory.

“It’s damn close,” said Rolf Densing, who heads the European Space Operations Centre in Darmstadt, Germany. “The farthest satellites are 36,000 kilometres out, so this is indeed a close miss,” he told AFP.

For researchers, the near miss will provide a rare chance to test Earth’s “planetary defence” systems — which at this point are focused on early warning rather than active asteroid deflection.

Observing TC4’s movements “is an excellent opportunity to test the international ability to detect and track near-Earth objects and assess our ability to respond together to a real asteroid threat,” said an ESA statement.  Asteroids are rocky bodies left over from the formation of our solar system some 4.5 billion years ago.  There are thought to be millions of them, most of them in a “belt” between the orbits of Mars and Jupiter.

A space rock slightly bigger than TC4, at 40 metres, caused the largest Earth impact in recent history when it exploded over Tunguska, Siberia, in 1908.

In 2013, a meteoroid of about 20 metres exploded in the atmosphere over the city of Chelyabinsk in central Russia with the kinetic energy of about 30 Hiroshima atom bombs.

The resulting shockwave blew out the windows of nearly 5,000 buildings and injured more than 1,200 people. It caught everyone unawares.

If an object the size of TC4 were to enter Earth’s atmosphere, “it would have a similar effect to the Chelyabinsk event,” said the ESA.

But Earth’s atmosphere stretches only a few hundred kilometres far, and TC4 will comfortably miss it. Also, it would likely behave very differently to the Chelyabinsk object.

“The Chelyabinsk meteoroid was a piece of comet and they are usually made of icy material,” said Densing. “Due to the icy nature it probably dissipated in the atmosphere… When we’re talking about asteroids, this is solid material. They are mostly made up of iron, so will not so easily dissipate their energy in the atmosphere.”

TC4 is unlikely to shed any debris into the atmosphere.

Even if it did, no evacuation would be required for an object this size, said Koschny, merely a warning for people to stay away from windows that could shatter from the shockwave.

Densing, who has previously warned that humanity is not ready to defend itself against an Earth-bound object, said he would not lose any sleep, not over this one.  “However, it makes you wonder what will happen next time,” he said.  “I would have felt a bit more comfortable if we… had a longer pre-warning time.”


WT1190F Splashdown Friday

(Email from Cattle Point Dark Sky Urban Star Park volunteer William Smith)

Dear Gerhard Drolshagen : On the Orbit of WT1190F (aka Snoopy)

Does object  get captured weeks before and go into earth’s orbit, slowly losing speed and descending? OR does it come shooting directly into the earth’s atmosphere – almost perpendicular to a tangent  ie pointing at the earth’s centre?  This is important because if it orbits the earth one or two times as it slows down, then we might see it in the dark of the late evening where we are on West Coast of North America..  

 Look here : https://www.pinterest.com/pin/564357397034893195/


If you look at the ISS paths then focus in on the one which crosses southern India, this might indicate that SNOOPY (coming also NW-> SE) would pass over Panana, Bahamas, Northern Spain , Mediterranean and then IRAN . No luck for west coast of USA/Canada where I am.  

Hello Bill,
Gerhard Drolshagen forwarded your message to me. Here is some of the info we have on WT1190F.

The object has been in Earth’s orbit at least since 2009. It has been moving in an elongated orbit with apogee at about twice the distance of the Moon, and perigee getting closer and closer to the Earth, until the upcoming re-entry. Since 2009, it has completed dozens of orbits around the Earth, and each orbit is about a month long.
The impact trajectory is not very vertical, but still much steeper than the typical re-entry of a low-orbiting satellite. It will come in with an angle of about 20° from the horizontal (=70° from vertical).

Given the fact that the orbit is so long, the geometry is totally different from a pass of the ISS. The latter orbits the Earth in about 90 minutes, while WT1190F takes weeks. So the current pass is actually the last part of the last orbit for this object.
Anyway, from a geometry point of view, it will definitely be observable from north America in the morning hours of November 12. However, it will be very faint, magnitude 19 or so, invisible by eye even with a large telescope. A CCD camera and at least a moderate-size telescope will be needed to get an image of it at that time.
Even for Europe and Northern Africa, which are the countries best-placed to observe it just hours before impact, it will only reach magnitude 15 or so, too faint for anything but images with a good telescope.

If you want to get an ephemeris for a specific site, I suggest you use this page from the Minor Planet Center: http://www.minorplanetcenter.net/iau/artsats/artsats.html. Just select WT1190F, enter the required information, and you will get your specific ephemeris based on the latest data.

Let us know if you need any additional info, and thanks for contacting us.

PS Young post-grads : http://hoyleshield.wesmith104.com/?page_id=80

For media : https://plus.google.com/communities/102562881766320685473


4 Meteor Showers and Comet Lovejoy

For the past few weeks you may have noticed meteors shooting across the sky. There is the Geminid meteor shower and three other smaller meteor showers in progress. Although with the bright moon, the dimmer meteors aren’t as easily seen.

The Geminids started Dec 4 and end Dec 17. On Sat Dec 14, at their peak they can give 120 meteors per hour. Fairly slow for meteors, they are travelling at a speed of 35 km/s. (That’s still pretty fast. For comparison, the International space station orbits at 8km/s, and goes around the Earth in 90 minutes.)

There are three smaller showers in progress: The sigma-Hydrids from Dec 03-Dec 15, peaked on Thurs Dec 12 with 3 meteors/hour, at speeds of 58km/s.
The Comae Berenicids from Dec 12-Jan 23 peaked on Monday Dec 16 with 3 meteors/hour, at speeds of 65km/s
And the December Leo Minorids from Dec 05-Feb 04 peak on Thurs Dec 19 with 5 meteors/hour at 64km/s

Don’t forget Comet Lovejoy in the early morning around 7am, before sunrise, a small fuzzy blob visible between Hercules and Corona Borealis above the eastern horizon. The bright moon drowns it out currently, so you’ll need binoculars or a telescope to see it and its slight tail.