The tail of the celestial sky could be more than 1.5 times the distance between Earth and Sun, according to a new measurement.
A celestial object can be so long that further measure the distance between the Sun and the Earth? It seems impossible, like trying to put an elephant in a hat, but it is very likely to be true. The giant called C/2006 P1 McNaught and is an old acquaintance, because three years ago became the brightest comet seen from Earth in nearly half a century. Now British scientists believe that this car blue can be the largest ever measured in the universe. The findings will be presented by the cientítico Geraint Jones, the Mullard Space Science Laboratory, London’s Global University (UCL), the National Astronomy Meeting being held these days in Glasgow.
The supermedidas come up with a new formula. The scientific team used data from the Ulysses spacecraft from NASA and the European Agency ESA, an unmanned probe designed to study the Sun at all latitudes. Instead of using the queue length to measure the scale of the comet, the objective was to measure the size of the region of space that was disturbed by his presence. The magnetometer data shows evidence of decay of shock waves around the comet. These waves are created when the ionized gas emitted by the comet’s nucleus joins the fast solar wind particles, causing the wind will slow sharply.
Comet McNaught became popular in 2007 when, in the months of January and February, it became the brightest visible from Earth in 40 years. Coincidentally, Ulysses crossed the comet’s tail during that time, one of three unplanned encounters with the debris of a heavenly fireball during his mission in 19 years. The probe found the ionized gas McNaught’s tail a distance from the nucleus of the comet more than 1.5 times the distance between Earth and the Sun, ie, 225 million kilometers. A huge length, much larger than the spectacular dust tail that was seen from Earth in 2007 and left behind other comets that also reach the millions of miles.
18 days to cross
However, “it was very difficult to observe the plasma tail of McNaught compared with the bright dust tail, so we can not estimate what its exact length,” says the head of the investigation. “What we can say is that Ulysses took him 2.5 days to cross the solar wind around the comet Hyakutake, while doing so in the McNaught cost no less than 18 days. This shows that the comet posed a major obstacle to the solar wind. ”
Another comparison with crossing times of other encounters with comets confirm the large scale of McNaught. The Giotto spacecraft crossed the comet Grigg-Skjellerup in 1992 and only took an hour to cross the region of shock waves. For Comet Halley, was enough a few hours.
For Jones, “the scale of an active comet output level depends on the gas instead of the size of the nucleus. The nuclei of comets are not necessarily total assets on their surfaces, which can say is that the level of gas production McNaught is clearly much greater than that of Hyakutake