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Cause of noises made by meteors found

Fireball Sound
© Spalding et. al./Scientific Reports
Bright, flaring meteors are sometimes accompanied by faint noises. What's strange about these popping, sizzling, rustling, and hissing sounds are that they reportedly occur almost instantly to earthly onlookers. This makes little sense, as meteors are as far as sixty miles away from viewers on the ground, so any sound they make should take several minutes be heard. What's going on? Do meteors somehow defy the laws of physics?

Researcher Richard Spalding and several of his colleagues at Sandia National Laboratories recently set out to study this strange phenomenon, and in a study just published to the journal Scientific Reports, they announce that the sounds are likely created through light.

Meteor fireballs sometimes pulse with light many times brighter than the full Moon, and these blasts can briefly heat the surfaces of objects many miles away. Such sudden temperature changes can actually create sound.

"We suggest that each pulse of light can heat the surfaces of natural dielectric transducers," Spalding and his colleagues write. "The surfaces rapidly warm and conduct heat into the nearby air, generating pressure waves. A succession of light-pulse-produced pressure waves can then manifest as sound to a nearby observer."

Fireball 4

Bright green meteor fireball illuminates skies over Wisconsin and Illinois

meteor fireball over Lisle
© American Meteor SocietyAMS Event#454-2017 – Caught on a Police Dashcam (Lisle, IL PD)
Over 170 reports from IL, WI, MI, IN, OH, IA, NY, Ontario, KY and MN

The AMS has received over 170 reports so far (and counting...) about of a fireball event over seen over Wisconsin on Wednesday, February 6th 2017 around 01:27CST (07:31 UT.). The green fireball was seen primarily from Illinois and Wisconsin but witnesses from Michigan, Indiana, Ohio, Iowa, New York, Kentucky, Minessota and Ontario (Canada) also reported the event.


Comet 2

Comet 45P approaches Earth - Closest approach on Feb. 11th

45P Honda-Mrkos-Pajdusakova
© Michael Jäger
A small comet named "45P/Honda-Mrkos-Pajdusakova" (45P for short) is approaching Earth. At closest approach on Feb. 11th, the comet will be 7.4 million miles from our planet, visible in binoculars and small telescopes. This is what it looks like (image on the left).

Michael Jäger of Stixendorf, Austria, took the picture on Dec. 31, 2016, just as the comet was swinging around the sun en route to Earth. Since then 45P's icy nucleus has been heated by solar radiation, causing it to spew brightening jets of gas into the comet's green atmosphere. Why green? Because the comet's vaporizing nucleus emits diatomic carbon, C2, a gas which glows green in the near-vacuum of space.

According to the Minor Planet Center, this is the 8th closest pass of any comet in the modern era (since ~1950, when modern technology started being used to study comets). It will only be 31 times farther from Earth than the Moon.

Interestingly, 45P made an even closer approach on its previous orbit (23 lunar distances), so it is also on the list as the 5th closest.

Proximity makes the comet bright despite its small size. Forecasters say 45P could be on the verge of naked eye visibility (6th magnitude) when it emerges into the pre-dawn sky later this week. The best time to look is during the dark hours before sunrise between Feb 9th and 12th. The comet will be racing through the constellation Hercules high in the eastern sky. Sky maps: Feb. 9, 10, 11, 12.

Got a great picture? First, submit it to Spaceweather.com. Next, send it to the Planetary Science Institute, which is collecting amateur images to help professional researchers study Comet 45P. More resources: 3D Orbit, Ephemeris.

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Bright meteor fireball captured over Caeté, Minas Gerais, Brazil

Fireball over Caete, Brazil
© Via Twitter@Rainmaker1973
Bright fireball captured over Caeté, Minas Gerais, Brazil on January 30, 2017.


Fireball 2

Asteroid attack? Yet another asteroid to give Earth a close shave

Another close shave
© ESASpace rock block party!
For the fourth time since the start of 2017, a small celestial body will pass closer to Earth than the distance between us and the moon. Recently discovered asteroid 2017 BS32 zips by around midday Thursday.

This latest narrow shave comes just a few days after the closest such flyby in months, prompting observers and some astronomers to wonder if the apparent blitz of tiny planetoids could be more than mere coincidence.

According to astronomer Paul Cox at the Slooh observatory, the apparent bursts of small, close-approaching asteroids were first spotted just before buzzing us initially sparked discussion in 2016.

"One possibility sprang to mind -- that these clusters of smaller asteroids making close approaches to Earth over relatively short periods of time were in fact the fragments from larger asteroids that had broken up," Cox said via email. "However, when we reviewed the orbits of each of the asteroids, we found no correlation between them -- showing clearly they weren't associated in any way."

Cox said the scientists also looked for a connection to seasonal changes or to weather at observatories that might reduce discoveries of nearby asteroids, but there was no conclusive data to be found.

Binoculars

Close encounter! Asteroid discovered yesterday whizzed 70,000 km from Earth

NEO 2017 BH30
The near-Earth asteroid 2017 BH30 was discovered by the Catalina Sky Survey in Arizona (USA) on 29 January 2017 and announced later the same day by the Minor Planet Center: it was going to have a very close encounter with the Earth, at 0.18 lunar distances (about 70.000 km).

At Virtual Telescope Project we captured 2017 BH30 while it was safely approaching us. Above is an image coming from the average of two 60-seconds exposures, remotely taken with "Elena" (PlaneWave 17″+Paramount ME+SBIG STL-6303E robotic unit) available at Virtual Telescope. The robotic mount tracked the fast (36″/minute) apparent motion of the asteroid, so stars are trailing. The asteroid is perfectly tracked: it is the sharp dot in the center, marked with two white segments.

To get these impressive results, the Paramount ME robotic mount tracked using the ephemerides retrieved via the JPL's Horizon webserver. At the imaging time, asteroid 2017 BH30 was at about 500.000 km from us and safely approaching. Its diameter should be around 5-10 meters or so.

The observations provided by the Virtual Telescope Project were published by the Minor Planet Center on its electronic circular MPEC 2017-B121.

Asteroid 2017 BH30 safely reached its minimum distance of about 70.000 km from us on 30 Jan. 2017 at 04:51 UT.

Over the years, our capability to detect small asteroids improved quite a lot, hence the apparently higher numbers of close approaches we see these days.

Comment: That would depend on how soon you want to detect them.

Forget About Global Warming: We're One Step From Extinction!


Fireball 3

Meteor fireball observed across 11 southern U.S. states

Fireball
If you saw a bright flash in the sky around 6:16 a.m., it wasn't lightning. It was a short trail, exploding fireball that lasted around three seconds.

Check out this still image captured by ArkansasSky.com near Greenbrier, Arkansas. They caught a big flash on their camera in the lower part of the sky between 20 and 30 degrees above the horizon.

There were several sightings in Collierville and scattered reports from Louisville, KY to Austin, TX. Check out the map to see all the sightings as of 9:30 a.m.

map meteor

Comment: The American Meteor Society (AMS) received 120 reports about a fireball seen over AR, TN, TX, MO, OK, KY, KS, IL, NE, LA and MS on Monday, January 30th 2017 around 12:13 UT.

AMS meteor fireball map 30.01.17
© AMS (screen capture)



Fireball

Meteor fireball spotted over Leeds, UK

Meteor over Leeds
© Yorkshire Evening PostThe meteor over Allerton Bywater.
Is this a meteor in the skies over Leeds?

Kelly Moss snapped the burning light hovering over Brigshaw High School in Allerton Bywater at around 4.30pm on Wednesday, as dusk was falling.

A meteor, often called a shooting star, is the visible passage of a glowing meteoroid, micrometeoroid, comet or asteroid through Earth's atmosphere, after being heated to incandescence by collisions with air molecules in the upper atmosphere, creating a streak of light via its rapid motion and sometimes also by shedding glowing material in its wake.

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Security camera captures meteor fireball lighting up the sky in Huntersville, North Carolina

Fireball over Huntersville, NC
© Via YouTube/rungoiron
Not sure what my security cam captured last night, but maybe there is a cute alien living in my neighbors backyard now! Huntersville, NC.


Comment: Another view from a dashcam in Watuga County, North Carolina:




Fireball

Mysterious boom rattles San Diego residents

San Diego
© 7 San Diego
Several people across San Diego County reported hearing a loud, mysterious boom Tuesday afternoon.

An NBC 7 viewer told us, around 3:18 p.m., she heard two loud booms that shook the windows in her home in Santee.

There were multiple posts on social media of people reporting their homes rattled from the boom. The posts were from residents across the county, including Clairemont, Santee, and San Diego.

Some wrote that they suspected the sounds were caused by a sonic boom, but NBC 7 has not confirmed that.

Comment: Fox News San Diego reports two large "bangs" were heard. Residents also reported a car moving back and forth and a "large glowing ball in the western sky".