Astronomers are excited about the possibility of a new meteor shower May 30-31. And that excitement 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 1am on the East Coast or 10pm on the West Coast.
We can’t be certain what we’ll see. We can only hope it’s spectacular.
Most stargazers will have a prime viewing opportunity to see the planets Mars and Jupiter draw incredibly close in the predawn sky on the nights of May 27-30.
The two planets will appear 20 degrees or so above the horizon in the eastern-southeastern sky, against the constellation Pisces, approximately 45 minutes before local sunrise. This Mars-Jupiter conjunction will be visible, barring local weather issues, in the predawn hours each morning from May 27 to May 30. The conjunction will peak at 3:57 a.m. CDT on May 29.
“Planetary conjunctions traditionally have been more the stuff of astrology than serious astronomy, but they never fail to impress during observations, particular when the gas giants are involved,” said Mitzi Adams, an astronomer and researcher at NASA’s Marshall Space Flight Center in Huntsville, Alabama.
During such a conjunction, two planets appear close together in Earth’s night sky. In the case of Earth’s solar system, conjunctions happen frequently because our sister planets travel around the Sun in a fairly similar ecliptic plane, often appearing to meet in our night sky despite being millions of miles away from one another.
At their closest point, Mars and Jupiter will be separated by no more than 0.6 degrees. Astronomers routinely use degrees to measure the angular distance between objects in the night sky. To observers on the ground, the distance between the two planets will be no more than the width of a raised finger, with Mars appearing just to the lower right of the massive gas giant.
It might be necessary to use binoculars or a telescope to spot Mars clearly, said Alphonse Sterling, a NASA astronomer who works with Adams at Marshall. But he noted that observers should have no trouble identifying Jupiter, even with unaided eyes.
“We anticipate Jupiter will shine at a magnitude of -2.2,” Sterling said. “Mars, in comparison, will have a magnitude of just 0.7.”
The brightness of celestial bodies is measured according to their magnitude value, a number which decreases as brightness increases. A negative value indicates the planet or moon is easy to see in the night sky, even with ambient light from one’s surroundings.
Mars and Jupiter are millions of miles away from us, of course – more than 136 million miles will separate Earth and Mars at the time of the conjunction, with Jupiter nearly four times further away. Even so, Jupiter will be the far brighter of the two. With its planetary diameter of around 4,200 miles, Mars is dwarfed by the massive Jovian giant, which has a diameter of about 89,000 miles. Being so much smaller, Mars reflects far less sunlight.
Mars also orbits the Sun more quickly, spinning eastward in our night sky fast enough to leave its lumbering gas-giant counterpart behind. Mars will catch up to Jupiter again and pass it during another conjunction in August 2024.
Adams and Sterling look forward to spotting the planetary conjunction.
“It’s thrilling to look up and recognize that these two worlds represent the breadth of NASA’s planned and potential goals for science and exploration,” Adams said. “As NASA prepares to send the first human explorers to the planet Mars, the possibilities could be virtually limitless for groundbreaking science discoveries among Jupiter’s fascinating moons.”
“This conjunction brings together two vastly different worlds, which both hold incredible promise to help us better understand our solar system, humanity’s place in the cosmos, and where we may be headed as a species,” Sterling added.
“Get outside before sunrise on May 29 and see them for yourself – and imagine all we’ve yet to learn from them,” he added.
Enjoy this celestial event as you watch the skies!
On the night of May 15, and into the early hours of May 16, skywatchers will be treated to a phenomenon which takes place every 1.5 years or so: a total lunar eclipse.
Total lunar eclipses occur when the Moon and Sun are on opposite sides of Earth and the planet casts a complete shadow, or umbra, over its sole natural satellite. There may be multiple partial lunar eclipses each year, but total eclipses are a bit rarer. Best of all, unlike the precautions one takes to observe a total solar eclipse, it’s completely safe to watch a lunar eclipse unfold with the unaided eye. Even so, binoculars or a powerful telescope definitely can enrich the experience.
The partial eclipse phase will begin over North America at 9:28 p.m. Central Daylight Time on May 15. Totality will begin at 10:29 p.m. CDT, concluding about midnight. After totality, the partial phase will end at 12:56 a.m. CDT on May 16.
This full Moon was known by early Native American tribes as the Flower Moon because this was the time of year when spring flowers appeared in abundance.
Mitzi Adams and Alphonse Sterling, both astronomers at NASA’s Marshall Space Flight Center in Huntsville, Alabama, are particularly excited to observe the lunar eclipse. One of the most recent such events they documented – in January 2018 – was very low on the horizon, with trees and buildings partially obscuring the eclipse during totality.
Then, of course, the global COVID-19 pandemic put a damper on eclipse watch parties in 2020-2021.
“It’s exciting to get back to holding astronomical society events in person, where it’s safer to share a telescope eyepiece,” Adams said.
Unlike a total solar eclipse – in which ideal viewing is limited to a roughly 100-mile-wide “path of totality” as the shadow of Earth’s Moon sweeps across the land relative to the position of the Sun – a lunar eclipse has no such limits.
“The whole half of Earth in darkness during those hours will be able to see it,” Sterling said. “You don’t have to work too hard to find a good vantage point. Just go outside!”
What can viewers expect to see? As Earth’s shadow deepens on the face of the Moon, it will darken to a ruddy, red color, with its intensity depending on atmospheric interference.
It’s no surprise observers coined the ominous-sounding phrase “blood moon,” but the effect is completely natural. During the eclipse, most visible-spectrum light from the Sun is filtered out. Only the red and orange wavelengths reach the surface.
The blocking of the Moon’s reflected light has another benefit, Adams said.
“No moon means more visible stars,” she said. “During totality, if the skies are clear, we may even be able to see the Milky Way itself, showing up as a hazy white river of stars stretching away in a curving arc.”
Sterling notes that the long duration of the total eclipse offers amateur shutterbugs plenty of time to experiment with photographing the event. He recommends trying varying exposure times with conventional cameras for maximum effect.
He and Adams both emphasize the value of putting the camera aside, as well.
“Just watch it happen,” Adams said. “Looking at the Moon, it’s hard not to think about the people who actually walked there, and about those who soon will do so again – when NASA’s Artemis program launches the next human explorers to the Moon in coming years.”
Sterling said the most valuable aspect of the event is the chance to spark wonder in young minds. “We don’t get a lot of groundbreaking astronomical information from lunar eclipses, but they’re a great way to inspire discussion and engage the astronomers and explorers of tomorrow,” he said.
Most particles are no bigger than dust and sand. Hitting the upper atmosphere at speeds up to 45 miles per second, they flare and burn up. On any given night, the average person can see from 4 to 8 meteors per hour. Meteor showers, however, are caused by streams of comet and asteroid debris, which create many more flashes and streaks of light as Earth passes through the debris field.
“It’s a perfect opportunity for space enthusiasts to get out and experience one of nature’s most vivid light shows,” Cooke said.
Eta Aquariids (May 5-6)
First up, on the night of May 5 and early hours of May 6, around 3:00 am CDT, is the eta Aquariid shower, caused by the annual encounter with debris from Halley’s comet – remnants of the comet’s tour through the solar system once every 75 or 76 years. Its radiant – or the point in the night sky from which the meteor shower appears to originate – is the constellation Aquarius. The shower is named for the brightest star in that constellation, eta Aquarii.
Until Halley’s comet is next visible from Earth in 2061, only the eta Aquariids – and their fall counterpart, the Orionid meteor shower, which is visible each October – mark the passage of this solar system visitor.
“It will be interesting to see if the rates are low this year, or if we will get a spike in numbers before next year’s forecast outburst,” Cooke said.
The annual meteor shower has the best rates for those in the Southern Hemisphere, but even in the Northern Hemisphere, if weather conditions are right, there is a possibility of seeing up to 30 meteors per hour. The waxing crescent Moon will set before the eta Aquariid radiant gets high in the sky, leaving dark skies for what should be an excellent show. Best viewing happens after 3 AM local time, so get up early.
Tau Herculids (May 30-31)
A possible newcomer this year is the tau Herculid shower, forecast to peak on the night of May 30 and early morning of May 31.
Back in 1930, German observers Arnold Schwassmann and Arno Arthur Wachmann discovered a comet known as 73P/Schwassmann-Wachmann, or “SW3, which orbited the Sun every 5.4 years. Being so faint, SW3 wasn’t seen again until the late 1970s, seeming pretty normal until 1995, when astronomers realized the comet had become about 600 times brighter and went from a faint smudge to being visible with the naked eye during its passage. Upon further investigation, astronomers realized SW3 had shattered into several pieces, littering its own orbital trail with debris. By the time it passed our way again in 2006, it was in nearly 70 pieces, and has continued to fragment further since then.
If it makes it to us this year, the debris from SW3 will strike Earth’s atmosphere very slowly, traveling at just 10 miles per second – which means much fainter meteors than those belonging to the eta Aquariids. But North American stargazers are taking particular note this year because the tau Herculid radiant will be high in the night sky at the forecast peak time. Even better, the Moon is new, so there will be no moonlight to wash out the faint meteors.
“This is going to 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. If the debris had slower ejection speeds, then nothing will make it to Earth and there will be no meteors from this comet,” Cooke said.