This infrared image from NASA’s Spitzer Space Telescope shows a fractured comet 73P/Schwassman-Wachmann 3 spewing along a path of leftover debris during its multiple flights around the sun. The flame-like bodies are the comet’s fragments and tails, while the dusty comet’s trajectory is the line connecting the fragments. credit: NASA
Astronomers are excited about the possibility of new meteor showers on May 30-31, the tau Hercules shower expected to reach its peak on the night of May 30 and in the early morning of May 31.
In 1930, German observers Arnold Schwassmann and Arno Arthur Wachmann discovered a comet known as 73P/Schwassmann-Wachmann, or “SW3,” that orbited the Sun every 5.4 years. Because it is so faint, SW3 was not seen again until the late 1970s, appearing very normal until 1995, when astronomers realized that the comet had become about 600 times brighter and went from a faint smudge to being visible to the naked eye as it passed. Upon further investigation, astronomers realized that SW3 had shattered into several pieces, scattering debris on its orbital path. By the time we came our way back in 2006, it was roughly 70 pieces, and it has continued to break up further ever since.
If it reaches us this year, the SW3 debris will hit Earth’s atmosphere very slowly, traveling at 10 miles per second – meaning meteorites much lighter than those belonging to eta Aquariids. But stargazers in North America took special note this year because tau Hercules radiation will be high in the night sky at the expected peak time. Even better, the moon is new, so there will be no moonlight to wash away the faint meteors.
“This would be an all-or-nothing event. If the debris from SW3 was traveling more than 220 miles per hour when it separated from the comet, we might see a nice meteor shower,” said Bill Cook, who leads[{” attribute=””>NASA’s Meteoroid Environment Office at NASA’s Marshall Space Flight Center in Huntsville, Alabama.
All the excitement from astronomers and the public has sparked a lot of information about the tau Herculids. Some has been accurate, and some has not.
We get excited about meteor showers, too! But sometimes events like this don’t live up to expectations – it happened with the 2019 Alpha Monocerotid shower, for example. And some astronomers predict a dazzling display of tau Herculids could be “hit or miss.”
So, we’re encouraging eager skywatchers to channel their inner scientists, and look beyond the headlines. Here are the facts:
- On the night of May 30 into the early morning of May 31, Earth will pass through the debris trails of a broken comet called 73P/Schwassmann-Wachmann, or SW3.
- The comet, which broke into large fragments back in 1995, won’t reach this point in its orbit until August.
- If the fragments from were ejected with speeds greater than twice the normal speeds—fast enough to reach Earth—we might get a meteor shower.
- Spitzer observations published in 2009 indicate that at least some fragments are moving fast enough. This is one reason why astronomers are excited.
- If a meteor shower does occur, the tau Herculids move slowly by meteor standards – they will be faint.
Observers in North America under clear, dark skies have the best chance of seeing a tau Herculid shower. The peak time to watch is around 1 a.m. on the East Coast or 10 p.m. on the West Coast.
We can’t be certain what we’ll see. We can only hope it’s spectacular.
