For the past few days, the media has been abuzz with one of the most peculiar astronomical observations for many years. As described in a recent paper on the arXiv preprint service, a faint star in the northern constellation Cygnus has been seen acting incredibly strangely.
The star, KIC 8462852 – somewhat hotter, younger and more luminous than our sun – was observed by the Kepler spacecraft for over four years, 24 hours per day, 365 days a year, along with more than 100,000 other stars in the same patch of sky.
Kepler was designed to monitor the brightness of those stars with exquisite precision, looking for tell-tale tiny “winks” that would indicate that they were orbited by planets.
And Kepler has found planets in abundance; more than 1,000 to date, with more being confirmed all the time.
But in the case of this faint star in Cygnus, it has found something else. Something unexpected. And we still have no idea what it is.
Some commentators have even suggested that the observations might represent the discovery of advanced alien life!
That might be something of a stretch, but it is certainly true to say that the current observations have astronomers baffled. But that isn’t a bad thing.
The Unexpected Through Astronomical History
Many of the greatest and most exciting discoveries in astronomical history were unexpected and serendipitous, and ended up greatly revolutionising our understanding of the universe. Usually, such discoveries were made as new or improved technology allowed astronomers to study the sky in new ways, or in more detail.
That’s exactly what’s happened here, with KIC 8462852. It’s purely because of the unique ability of Kepler to study hundreds of thousands of stars continually for years at a time that the unusual behaviour was found.
Here are just three examples of how serendipity has driven astronomical understanding:
The Solar System’s First ‘New’ Planet
In 1781, using a homemade telescope Sir William Herschel discovered Uranus while scouring the sky looking for double stars. In one fell swoop, Herschel’s discovery doubled the radial scale of our solar system, and gave birth to the search for other planets. The chance find eventually led to the discovery of Neptune, through its gravitational pull on Uranus.
The idea that there could be more planets in our solar system also led to the scouring of the sky that found the first asteroids in the early 1800s. The first asteroid found (Ceres) was another serendipitous discovery!
Although some astronomers were searching for objects between the orbits of Mars and Jupiter, Giuseppe Piazzi was instead constructing a new catalogue of stars. As he scoured the sky, he stumbled on the faint moving asteroid, purely by chance.
From those humble beginnings, we now know of hundreds of thousands of asteroids orbiting between Mars and Jupiter. We have also found tens of thousands of similar small bodies further from the sun (the planetary Trojans, and the trans-Neptunian objects).
Our knowledge of these objects, their distribution and their sizes, has been an incredible boon to scientists trying to disentangle the story of our solar system’s formation and evolution.
Bird Poop in Our Telescope or the Big Bang?
In the early 1960s, there was great debate over the origin of the universe. The two leading theories – the Big Bang and Steady State models – had been developed in response to the observed expansion of the universe (another serendipitous discovery, in the early part of the 20th century, by Vesto Slipher and others).
Theorists studying the two models were striving to make predictions of what we might observe in each case. A number of scientists had pointed out that if the universe had been created in a Big Bang, and was once smaller, denser and hotter than it is today, then a relic of that heat should be observable to the current day.
As a result, astronomers at Princeton University were in the process of preparing a survey to search for that “relic radiation”. At the same time, just down the road, Arno Penzias and Robert Wilson were testing a new 6m horn antenna radio telescope.
That telescope was highly sensitive, and Penzias and Wilson were attempting to characterise its performance, and to remove known sources of interference so that it could be used to maximum effect.
