Krakatau Volcano, Indonesia April 22, 2008
Alert status at Krakatau Volcano, Indonesia has been
raised to Level 2. Since April 15th there has been an
increase in volcano earthquakes. Ash emissions resumed
at Anak Krakatau Volcano. Booming noises were heard at
Pesauran 42 km from the volcano.
Wednesday 23 April 2008
Sunday 20 April 2008
Saturday 19 April 2008
Sun tsunami
Astronomers have captured the first footage of a solar "tsunami" hurtling through the Sun's atmosphere at over a million kilometres per hour.
The event was captured by Nasa's twin Stereo spacecraft designed to make 3D images of our parent star. Naturally, this type of tsunami does not involve water; instead, it is a wave of pressure that travels across the Sun very fast. Details were reported at the UK National Astronomy Meeting in Belfast. In half an hour, the tsunami covered almost the full disc of the Sun.In a solar tsunami, a huge explosion near the Sun, such as a coronal mass ejection or flare, causes a pressure pulse to propagate outwards in a circular pattern.
Last year's solar tsunami, which took place on 19 May 2007, lasted for about 35 minutes, reaching peak speeds about 20 minutes after the initial blast.
Co-author David Long, from Trinity College Dublin (TCD), Ireland, commented: "The energy released in these explosions is phenomenal; about two billion times the annual world energy consumption in just a fraction of a second.The shockwave moved out exactly like a tsunami on Earth. "A series of troughs and crests in pressure causes it to propagate outwards. But on the Sun, it is hot gas."
When a person talks to someone in a room, their voice is carried by pressure waves in the gas that's between them; it's the much the same on the Sun except on the Sun, magnetic fields also help the waves along. The phenomenon is therefore known as a magneto-acoustic wave.
The event was captured by Nasa's twin Stereo spacecraft designed to make 3D images of our parent star. Naturally, this type of tsunami does not involve water; instead, it is a wave of pressure that travels across the Sun very fast. Details were reported at the UK National Astronomy Meeting in Belfast. In half an hour, the tsunami covered almost the full disc of the Sun.In a solar tsunami, a huge explosion near the Sun, such as a coronal mass ejection or flare, causes a pressure pulse to propagate outwards in a circular pattern.
Last year's solar tsunami, which took place on 19 May 2007, lasted for about 35 minutes, reaching peak speeds about 20 minutes after the initial blast.
Co-author David Long, from Trinity College Dublin (TCD), Ireland, commented: "The energy released in these explosions is phenomenal; about two billion times the annual world energy consumption in just a fraction of a second.The shockwave moved out exactly like a tsunami on Earth. "A series of troughs and crests in pressure causes it to propagate outwards. But on the Sun, it is hot gas."
When a person talks to someone in a room, their voice is carried by pressure waves in the gas that's between them; it's the much the same on the Sun except on the Sun, magnetic fields also help the waves along. The phenomenon is therefore known as a magneto-acoustic wave.
Thursday 10 April 2008
Solar tsunami
Astronomers have captured the first footage of a solar "tsunami" hurtling through the Sun's atmosphere at over a million kilometres per hour.
Naturally, this type of tsunami does not involve water; instead, it is a wave of pressure that travels across the Sun very fast.In a solar tsunami, a huge explosion near the Sun, such as a coronal mass ejection or flare, causes a pressure pulse to propagate outwards in a circular pattern. Last year's solar tsunami, which took place on 19 May 2007, lasted for about 35 minutes, reaching peak speeds about 20 minutes after the initial blast.
Co-author David Long, from Trinity College Dublin (TCD), Ireland, commented: "The energy released in these explosions is phenomenal; about two billion times the annual world energy consumption in just a fraction of a second on the Sun, magnetic fields also helped the waves along. The phenomenon is therefore known as a magneto-acoustic wave.
Stereo's Extreme Ultraviolet Imager (EUVI) instruments monitor the Sun at four wavelengths, which allowed astronomers to see how the wave moved through the different layers of the solar atmosphere. "We were able to show for the first time that this wave actually propagates almost all the way from the surface of the Sun to high up in the Sun's atmosphere," said Dr Gallagher. The researchers even saw the pressure wave bouncing off irregular regions of the Sun’s atmosphere, generating reflections or diffraction patterns - exactly as tsunamis have been observed to do on Earth when they crash against land.
Naturally, this type of tsunami does not involve water; instead, it is a wave of pressure that travels across the Sun very fast.In a solar tsunami, a huge explosion near the Sun, such as a coronal mass ejection or flare, causes a pressure pulse to propagate outwards in a circular pattern. Last year's solar tsunami, which took place on 19 May 2007, lasted for about 35 minutes, reaching peak speeds about 20 minutes after the initial blast.
Co-author David Long, from Trinity College Dublin (TCD), Ireland, commented: "The energy released in these explosions is phenomenal; about two billion times the annual world energy consumption in just a fraction of a second on the Sun, magnetic fields also helped the waves along. The phenomenon is therefore known as a magneto-acoustic wave.
Stereo's Extreme Ultraviolet Imager (EUVI) instruments monitor the Sun at four wavelengths, which allowed astronomers to see how the wave moved through the different layers of the solar atmosphere. "We were able to show for the first time that this wave actually propagates almost all the way from the surface of the Sun to high up in the Sun's atmosphere," said Dr Gallagher. The researchers even saw the pressure wave bouncing off irregular regions of the Sun’s atmosphere, generating reflections or diffraction patterns - exactly as tsunamis have been observed to do on Earth when they crash against land.
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