Hobby astronomers discover asteroids, map galaxies and help in the search for meteorites. But how useful is their data for researchers?
On clear nights, Erwin Schwab peers deep into the solar system from the observatory on Kleiner Feldberg, a mountain in Germany’s Taunus range. He’s on the lookout for celestial bodies that have eluded professional astronomers: small minor planets up to several kilometres in diameter, such as asteroids, that orbit the sun and sometimes can come dangerously close to Earth.
An amateur astronomer who works at the nearby GSI Helmholtz Centre for Heavy Ion Research, Schwab discovered 86 celestial bodies between 1998 and 2009, 31 of which he was allowed to name himself. They include Skywalker and Tatooine, named after the protagonist of the “Star Wars” saga and his home planet.
“At my day job I deal with the world of microphysics, and as a hobby with the celestial cosmos,” he says and gives a hearty laugh.
“If you observe something meaningful, it makes no difference whether you’re a salaried professional astronomer or a well-equipped amateur,” remarks Sven Melchert, chairman of the Vereinigung der Sternfreunde, a Germany-wide group of amateur astronomers who’s name translates roughly as Stargazers Society.
The amateur astronomy boom sparked by the introduction of easy-to-use digital single-lens reflex cameras – well-suited to astrophotography – has meanwhile subsided. Automatic sky-scanning telescopes now used by professional astronomers lowered amateurs’ share of discoveries from 17.1 per cent in 1997 to 1.6 per cent in 2017, according to data from the Minor Planet Center, which operates at the Smithsonian Astrophysical Observatory outside the US city of Boston.
There are about 50 minor-planet hunters in Germany, according to Schwab, the seventh-most successful among them.
As Melchert notes, most of the some 200 astronomical observatories in Germany have difficulty finding new blood. “Young people come and go, but it wasn’t any different 20 years ago,” he says.
Amateur astronomers provide valuable assistance, such as observing variable stars or searching for meteorites – asteroids or meteoroids that have fallen to Earth – points out Axel Quetz, spokesman for the Max Planck Institute for Astronomy in Heidelberg, Germany.
“No professional astronomer has time to look for meteorites – amateurs do,” Quetz says, adding that the finds are useful to astronomers in understanding the solar system’s mineral composition.
To determine the shape and size of a minor planet, astronomers have to join forces. Its diameter can be measured only during a stellar occultation – ie, when it passes in front of a star, temporarily blocking the star’s light as seen from Earth.
“Many observers have to be stationed at different locations in order to accurately measure the small shadow that’s cast” – a task that has typically fallen to amateurs – Schwab says.
The data are important in planning potential landing manoeuvres on the space rocks or defensive strategies should they threaten Earth.
But even people without any astronomical training or expertise can participate in space projects, for example on the citizen science web portal Zooniverse. Under the maxim that “many eyes see more than two,” anyone with a computer can map the Milky Way, identify weather phenomena on Mars and classify the morphology of galaxies.
“They guide you [on the portal], and then you can do it yourself. Not even pros are better,” Quetz says.
To classify galaxies in the Zooniverse project Galaxy Zoo, you click through countless images of glimmering whitish or reddish galaxies that you’re supposed to differentiate according to shape – say, spiral or elliptical.
“Humans are really still superior at this task,” Quetz says, explaining that computers can only recognise patterns they’ve been programmed to recognise.
In 2007, a Dutch schoolteacher named Hanny van Arkel discovered a strange green object while browsing through Galaxy Zoo images. Thought to be what’s known as a quasar light echo, it was dubbed Hanny’s Voorwerp, Dutch for Hanny’s Object. It wouldn’t have been detected with a computer algorithm.
Computers are by no means useless in astronomy though. With their help, professional astronomers simulate the distribution of dark matter in the universe, for instance.
“With the platform BOINC you can provide computation time with your private computer to search for gravitational waves, pulsars or signals from extra-terrestrials,” Quetz says. BOINC stands for Berkeley Open Infrastructure for Network Computing, free software from the University of California, Berkeley, that harnesses the processing power of millions of computers to evaluate data.
But it’s the power of intellectual curiosity that makes the more than 14,500 participants of Galaxy Zoo stare at images of the universe, and amateur astronomer Schwab to stare at the starry night sky.
He says he’s now even allowed to telecontrol large European Space Agency telescopes for his research. “Discovering a minor planet is awesome,” he says. “It really gives you a jolt of adrenaline.” – dpa
