Astronomers have been trying to predict a “storm” of the Tau-Herculides meteor shower for years. The long-awaited rare phenomenon may occur next week, with the possibility of thousands of “star meteors” appearing per hour, if the forecast is confirmed.
If the most optimistic scenario works, our atmosphere should reach 100,000 meteors per hour at 16 km/s, considered low. Thus, the luminous streaks move slowly and long, and remain in the sky for a longer time.
The potential storm peak is expected to occur between Monday and Tuesday (May 30-31). This phenomenon will be better observed from the northern hemisphere, but the possibility that it will generate a beautiful spectacle in the sky of Brazil is not excluded.
Tau-Herculids consists of debris from comet 73P/Schwassmann-Wachmann 3 (SW3), which is disintegrating. At this time each year, between late May and early June, the ground crosses the trail of dust and small rocks left behind in the earlier passes.
This shower is usually more conservative, with two or three meteors an hour. “There was more intense activity in 1930, when it was first seen. After that, it became very weak,” says the amateur astronomer. lauriston Trinidad Member Bramon (Brazilian Meteorite Monitoring Network).
Storm or rain?
It has been nearly 200 years since we witnessed a phenomenon of this kind and severity. The last time occurred in 1833, in the Leonids rain—which caused panic in the United States (imagine, at the time, waking up at dawn with thousands of lights twinkling in the sky; would it be the end of the world?).
‘Storm’ is a term for meteor showers that are characterized by unusual and extremely severe outbreaks. They usually arise after an asteroid or comet “parent” fragmentation – a process that leaves a thick cloud of ejected particles into space.
“Over time, this cloud disperses into the parent body’s orbit, forming annual meteor showers. Therefore, the more recently the fragmentation has occurred, the denser the cloud, and the more intense the resulting meteor storm,” Bramon explains.
Comet SW3 was discovered in 1930 by German observers Arnold Schwassmann and Arno Arthur Wachmann. It was calculated to have a core about 1.5 kilometers in diameter – relatively small – that orbits the Sun every 5.4 years.
But it disappeared from our skies for decades, only to reappear in 1979, with a natural appearance.
However, in 1995, its brightness suddenly increased: it was about 600 times brighter, and it became visible even with the naked eye. Until then, it was just a spot on telescopes.
“A month later, the astronomers discovered that the nucleus had split into some large clumps during the flight. The observations indicated at least four large fragments, two of which were clearly in the process of disintegration,” Trindade recalls.
In 2006, when it was heated up on its return to the interior of the solar system, the situation worsened: in March, there were already eight fragments; In April dozens. In May, nearly 70, along a vast trail.
The largest remains in orbit, where it acts as a multiple core. Eventually, the comet may completely disintegrate and become invisible.
Bramon believes that “the ruptures generated fragments of various sizes, and a huge amount of dust was thrown into space. Calculations indicate that on the night of May 30 to 31, the Earth will vertically cross a dense area of debris,” Bramon believes.
When these tiny rocks reach Earth’s atmosphere at high speed, they are actually burned and vaporized by friction, producing a luminous phenomenon called a meteor (“meteor”).
Uncertainty about this phenomenon
Since the split in 1995, astronomers have made calculations to predict this storm. “The great difficulty in predicting meteorite dates and rates is knowing exactly how fast the particle is expelled during the disintegration of large masses,” Trindade explains.
Studies show that, this year, Earth will pass through the debris cloud left by Comet 73P in five previous passes: 1892, 1930, 1941, 1979 and 1995 (when the collapse occurred).
“All expectations are that it will be very high activity. But we know that there are chances that the calculations will fail, because it is something unprecedented and we do not have enough data,” he adds.
The offer is not yet guaranteed. According to NASA, it will be an “all or nothing” moment: if particles are ejected from the nucleus during the disintegration of a comet at a speed of at least 354 km / h, we will experience a beautiful storm. Otherwise, they wouldn’t hit our atmosphere – we wouldn’t see meteors.
“It is not possible to predict accurately. Nothing may happen, it can be light and heavy rain, even a meteor storm, a rare and inspiring sight,” says Marcello de Sico, astronomy coordinator for the Exoss Project. Collaborative Meteorites Research.
how to watch
Despite its name, the radiant star (the point where meteorites converge) of the Tau-Herculids is the constellation Boieiro, known for the bright stars Arcturus and Vega.
Just find it, head northwest and look around carefully. A compass or astronomy app (eg Stellarium, Star Walk, Star Chart, Sky Safari, SkyView) can help.
The best places on the planet to follow this phenomenon are Mexico and the United States. The bad news for us is that, here in the Southern Hemisphere, the beam will be very close to the horizon, which makes observing a bit difficult. In Brazil, we can see between 10% and 50% of meteors – and the further north the country, the higher the chances.
“It sounds small, but if the best-case scenario is confirmed, it could mean tens of thousands of meteors per hour, which would be amazing,” Trindade highlights. The good news is that the moon in the new phase, without brightness, will make the sky darker. Thus, even the least intense meteors can be observed.
The recommendations are the same for all rain: find a place with less light pollution, with a good field of view, get comfortable and wait, looking at the entire area around the radiation. The phenomenon is visible to the naked eye without the need for any special equipment.
According to Bramon, at least three outbreaks should occur for Tau-Herulds:
- May 31, 12:10 a.m. ET: Earth will cross debris trails left by comets in 1892 and 1941. They are expected to hit 50 meteors per hour.
- May 31 2:10 a.m.: Earth will reach its 1979 trajectory and so will the thick cloud from the 1995 rupture. Since it’s the first time in history that we’ve interacted with these particles, time may vary (and may not even occur). Basic modeling suggests a rate of 600 to 700 meteors per hour. “However, given that the comet broke into several pieces in 1995, the intensity of this outbreak could be as high as 10,000, or perhaps 100,000 meteors per hour during its maximum,” Bramon optimistically believes.
- June 25, 11:58 p.m.: Earth will meet the trail left by the 1930 pass. The intensity will be much lower, with about three meteors per hour.
Outbreaks are unpredictable and short-lived, so watch out. “Due to the uncertainty about the orbital position of other parts of comet SW3, we recommend that observations be made from May 28 to June 1, always at dawn, with the possibility of seeing many meteors coming from the northwest direction, close to the radiation,” stresses de Sico.