* Astronomy

The Daytime Beta-Taurids meteor peaks in the constellation Taurus at 10:00 UT, 28th June, 2013.

ZHR: 10.0 
Velocity: 31.0km/s 

Radiant (J2000): RA=5.7h/85° Dec=23.5° 

The stream is active from the 5th June to the 17th July

Title: Effects of the large June 1975 meteoroid storm on Earth's ionosphere
Authors: P. Kaufmann, V.L.R. Kuntz, N.M. Paes Leme, L.R. Piazza, J.W.S. Vilas Boas, K. Brecher and J. Crouchley

The June 1975 meteoroid storm detected on the moon by the Apollo seismometers was the largest ever observed. Reexamination of radio data taken at that time showed that the storm also produced pronounced disturbances on Earth, which were recorded as unique phase anomalies on very low frequency (VLF) radio propagation paths in the low terrestrial ionosphere. Persistent effects were observed for the major storm period (20 to 30 June 1975), including reductions in the diurnal phase variation, advances in the nighttime and daytime phase levels, and reductions in the sunset phase delay rate. Large nighttime phase advances, lasting a few hours, were detected on some days at all VLF transmissions, and for the shorter propagation path they were comparable to solar Lyman alpha daytime ionisation. Ion production rates attributable to the meteor storm were estimated to be about 0.6 to 3.0 ions per centimetre cubed per second at the E and D regions, respectively. The storm was a sporadic one with a radiant (that is, the point of apparent origin in the sky) located in the Southern Hemisphere, with a right ascension 1 to 2 hours larger than the sun's right ascension.

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The storm has been interpreted as arising from a meteoroid cloud with a diameter of 0.1 au and a total mass of 10^13 to 10^14 g [Duennebier et al.] have estimated that a total mass of fragments of about 1.8 x 10^6 g collided with the moon during the event.

At the end of June our planet cuts across a part of space littered with debris that some astronomers believe has caused devastating impacts on Earth during recorded history.
Most of this debris is nothing more than specks of ice and dust, some of which enters our atmosphere and burns up in a flash.
But every so often the Earth encounters something much larger lurking in the debris trail: tower block-sized chunks of a comet that entered our solar system thousands of years ago.
Travelling at more than 100,000kph, these are big enough to survive entry through the atmosphere, and they could strike with the explosive violence of dozens of H-bombs.
This may sound like another of those terrifying yet incredibly rare events scientists seem so keen to scare us with these days.
But this is no once-in-a-million-years scenario. There is now impressive evidence that just such a cosmic impact happened barely a century ago.
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