Fireballs
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Telescope

Astronomers detect space rock 3 days after it passes close to Earth

Eddie Irizarry
EarthSky
Tue, 25 Jul 2017 13:21 UTC
Artists rendering of an asteroid passing Earth
© Earth SkyArtist’s concept of an asteroid passing near Earth.
A space rock now designated as asteroid 2017 OO1 was detected on July 23, 2017 from the ATLAS-MLO telescope at Mauna Loa, Hawaii. An analysis of its trajectory revealed it had been closest to Earth on July 20 sometime between 10:27 p.m. to 11:32 p.m. EDT (between 02:27 to 03:32 UTC on July 21).

This means the asteroid's closest approach occurred 2.5 to 3 days before it was seen. Asteroid 2017 OO1 flyby had passed at about one-third the Earth-moon distance, or about 76,448 miles (123,031 km).

Although that's still a safe distance, a fact that stands out is that asteroid 2017 OO1 is about three times as big as the house-sized asteroid that penetrated the skies over Chelyabinsk, Russia in February, 2013, breaking windows in six Russian cities and causing more that 1,000 people to seek treatment for injuries, mostly from flying glass.
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Comet

Comets from oort cloud more common threat to Earth than previously thought


Daily Galaxy
Wed, 26 Jul 2017 01:28 UTC
Comet
© NASA/JPL-Caltech
"Comets travel much faster than asteroids, and some of them are very big," said Amy Mainzer, co-author based at NASA's Jet Propulsion Laboratory, Pasadena, California, and principal investigator of the NEOWISE mission. "Studies like this will help us define what kind of hazard long-period comets may pose."

"The number of comets speaks to the amount of material left over from the solar system's formation," said James Bauer, lead author of the study and now a research professor at the University of Maryland, College Park. "We now know that there are more relatively large chunks of ancient material coming from the Oort Cloud than we thought."

Comets that take more than 200 years to make one revolution around the Sun are notoriously difficult to study. Because they spend most of their time far from our area of the solar system, many "long-period comets" will never approach the Sun in a person's lifetime. In fact, those that travel inward from the Oort Cloud -- a group of icy bodies beginning roughly 186 billion miles (300 billion kilometers) away from the Sun -- can have periods of thousands or even millions of years.

This illustration shows how scientists used data from NASA's WISE spacecraft to determine the nucleus sizes of comets. They subtracted a model of how dust and gas behave in comets in order to obtain the core size.
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Comet 2

New Comet: C/2017 O1

Ernesto Guido
Remanzacco Blogspot
Tue, 25 Jul 2017 18:58 UTC
CBET nr. 4414, issued on 2017, July 24, announces the discovery of a comet (magnitude ~15.3) in the course of the "All-Sky Automated Survey for Supernovae" (ASASSN) program, from images taken with the 14-cm "Cassius" survey telescope at Cerro Tololo on July 19.32 UT. The new comet has been designated C/2017 O1.

I performed follow-up measurements of this object, while it was still on the neocp. Stacking of 10 unfiltered exposures, 60 seconds each, obtained remotely on 2017, July 23.7 from Q62 (iTelescope network) through 0.50-m f/6.8 astrograph + CCD + f/4.5 focal reducer, shows that this object is a comet with a sharp central condensation surrounded by diffuse coma about 3 arcmins in diameter.

My confirmation image (click on it for a bigger version)
Comet C/2017 O1
© Remanzacco Blogspot
Below you can see the discovery image by ASASSN survey
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Fireball 2

Meteor fireball observed over São Paulo, Brazil

Exoss Citizen Science
YouTube
Tue, 18 Jul 2017 22:10 UTC
YouTube/Exoss Citizen Science (screen capture)
YouTube/Exoss Citizen Science (screen capture)
On July 17th, just four days after rattling windows and shaking walls scare residents in the region of Campinas, another fireball is registered in the State of São Paulo by Exoss Citizen Science, a Brazilian meteor monitoring organization.

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Fireball 5

What it would take to kill all life on Earth

Giorgia Guglielmi
Science
Fri, 14 Jul 2017 05:00 UTC
Asteroid impact on earth
© Zloyel/iStock
A giant asteroid crashing into our planet would instantly kill off millions of animals. But the aftermath of such an impact would be even more disastrous: Tsunamis, earthquakes, and vast clouds of dust blocking out the sun would lead to crop failure and mass extinction.

Sixty-five million years ago, just such an event killed off 75% of species on Earth. But to really wipe life off the planet, it would take an astrophysical event so powerful that Earth's oceans would literally boil away, according to a new study. The heat and cosmic radiation would make Earth inhospitable even to tardigrades, among the hardiest organisms ever discovered.

"They've taken a grand question—how resilient is life?—and turned [it] into a well-posed calculation, by focusing on the energy required to boil Earth's oceans," says Joshua Winn, an exoplanets expert at Princeton University, who was not involved in the study. "It's an awful lot of energy."
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Fireball 2

Meteor rattles windows and scares residents in Campinas, Brazil


G1 - Eptv
Fri, 14 Jul 2017 17:48 UTC
Photo of the Observatory of Campinas shows meteor trajectory in the sky
© EPTVPhoto of the Observatory of Campinas shows meteor trajectory in the sky
Noise and tremor scare residents of Hortolândia and Sumaré on Thursday night

The Municipal Observatory of Campinas (SP) caught the passage of a meteor in the region on Thursday night (July 13th). The cameras captured the moment when a luminous ball appears in the sky. See the meteor's trajectory in the video above. Residents reported feeling the shaking walls and windows and a loud noise.

Astronomer Júlio Lobo explains that "When a meteor falls and explodes, it causes a sonic boom, which usually shakes the walls and windows. [...] When this happens, it produces a meteorite, which is the 'pebble' that will stay on the ground. So if anyone happened to see a falling meteor, communicate us because this is of great scientific importance".

According to the astronomer, the Campinas observatory currently has six cameras, and this is the largest number of cameras in a Brazilian observatory. Many other meteors were recorded on Thursday night.

"We recorded 88 meteors on the same night. There is a network that studies this officially," said the astronomer.


Comment: It is well worth remembering what can come out of the sky, without any warning at all, like the Chelyabinsk meteor fireball.


Even NASA's own space data supports citizens' recent observations, namely the inconvenient fact that meteor fireballs are increasing dramatically.

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Fireball

Loud boom over North Carolina caused by meteor fireball


WLOS
Fri, 14 Jul 2017 21:48 UTC
Meteor over NC
© American Meteor SocietyThe American Meteor Society received about 50 reports about a fireball seen over the Southeast late Thursday night. This map shows places that reported seeing the fireball.
The American Meteor Society received about 50 reports about a fireball seen over the Southeast late Thursday night.

AMS said the fireball was seen shortly after 10 p.m. in North Carolina, South Carolina, Alabama, Tennessee, Georgia, Virginia and Kentucky and Tennessee.

Because there was nothing other than the fireball reported in the area at the time of the boom, speculation is that the boom was likely a meteor breaking up in the atmosphere.

Click here to see the AMS report.
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Fireball 3

Meteor fireball explodes over South Australia (VIDEOS)

Emma Pedler and Daniel Keane
ABC Online
Thu, 06 Jul 2017 07:32 UTC
South Australia meteor fireball
© facebook/Matthew Graziano (screen capture)
Six days after a suspected meteor shook Streaky Bay and very briefly lit up parts of South Australia's night sky, the event remains the talk of the town.

CCTV images of the spectacle show a bright light in the sky, lasting a couple of seconds, just before midnight on Friday, with locals reporting a thunder-like rumble a few minutes later.

Those lucky enough to have witnessed the event have described an "orange fireball" which could be seen from across the West Coast and Eyre Peninsula and as far afield as Elliston, Port Lincoln, Whyalla, Riverton and even Mount Barker, near Adelaide.


Comment: See also: Possible fast moving meteor fireball sighted over South Australia

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Fireball 5

88 pound meteor strikes the moon causing a massive explosion

Paul Baldwin
Express
Thu, 13 Jul 2017 16:59 UTC
meteor strike
© GettyThe moon was struck by a meteor creating an explosion visible with the naked eye.
A METEOR with the explosive power of TEN cruise missiles has struck the Moon - sparking a massive explosion visible with the naked eye.

And terrifyingly the 56,000 mph collision - captured by NASA scientists highlighting the catastrophic danger planet earth faces from similar meteors - was caused by a space rock weighing no more than 88 lbs (40 kilos).

Despite the meteor's tiny proportions - about the size of a small boulder and the weight of an average 10-year-old boy - the impact damage was colossal and the explosion shone with the brightness of a magnitude 4 star.
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Fireball 5

Tunguska impact of 1908: Witnesses describe what it's like to live through a meteor strike

K. N. Smith
Forbes
Fri, 30 Jun 2017 06:52 UTC
Tunguska blast
© Denys, Wikimedia CommonsThe Tunguska blast affected hundreds of square miles of northern Russia.
109 years ago today, a meteor crossed paths with Earth and blew apart in the air above a remote area of northern Russia, near the Tunguska River, on June 30, 1908.

Wind from the blast flattened trees for hundreds of miles, and the shock wave it sent through the ground would have registered a 5.0 on the Richter scale. The dying meteor exploded with a force estimated to be on par with the earliest nuclear bombs, around 15 megatons, although estimate range from 3 megatons to 30. (It's hard to say much for sure about the Tunguska object, because it left no crater, and no fragments have ever been found -- though not for lack of searching.) It could have flattened a major city. Fortunately, it struck in a remote area of the Russian taiga.

The director of the meteorological observatory at Irkutsk, whose seismographs recorded the impact, gave questionnaires to witnesses in the region and published a collection of their responses in 1924. Locals describe a fireball in the sky, multiple thunderclaps, a blast of heated wind, and a rumbling of the Earth.
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