Every star we see in the night sky is like our sun. Sure, some are larger or smaller, and some are hotter or cooler, but all work the same way.
Each is a thermonuclear fusion reactor that converts millions of tons of hydrogen into helium each second and, in the process, releases energy — some of which we see as light.
Also like our sun, most stars are home to planetary systems. Despite these not being visible to the human eye, this has been a topic of study for many centuries.
As far back as 2,000 years ago, ancient Greek thinkers conducted vigorous debates on the subject.
It wasn’t until 1983 that the Infrared Astronomical Satellite detected a dusty disk around the bright star Vega, producing the first evidence of a planetary system in formation.
Since that time, astronomers have found other such protoplanetary disks around other stars, but in 1995 they made a stunning discovery. They found the first actual planet orbiting the star known as 51 Pegasi some 50 light-years away.
And if you think this wasn’t a big deal, this discovery won the Nobel Prize in 2019!
The newly found planet was known to astronomers as 51 Pegasi b, but in 2015 the International Astronomical Union announced that it had assigned it an official proper name: Dimidium.
Today, we can count more than 7,300 planets and more than 5,000 planetary systems orbiting nearby stars.
The technology for finding these has improved so much in the past quarter-century that their number rises significantly every year.
If you’d like to keep up with the rapid pace of planet discoveries, visit both exoplanet.eu/catalog and science.nasa.gov/exoplanets and have a look around!
So what about that first dusty disk found around Vega some four decades ago? Do we know any more about it? Is it, in fact, the beginnings of a new planetary system?
Great questions, all!
When the Hubble Space Telescope was launched in 1990, astronomers aimed it toward Vega and saw reflected light from dust the size of smoke particles mostly on the edge of a 100 billion-mile-wide disk.
In 2005, they used the infrared Spitzer Space Telescope to map this dusty ring but couldn’t see much detail — at least, not enough to determine if there existed any clumps that would ultimately form planets.
And this year, the new James Webb Space Telescope aimed its 6-meter diameter infrared-sensitive eye toward Vega for an even closer look.
From its perch a million miles above the Earth, it resolved the glow of warm sand-sized particles and found the disk to be remarkably smooth.
In other words, there appeared no evidence of planets within, nor even clumpiness in the disk that might eventually lead to the birth of planets.
This is an important finding because it throws into question our understanding of how planets and planetary systems come to be and opens an entirely new path for astronomers to explore.
Step outside this week to check out Vega; it’s the brightest star low in the western sky after dark.
Of course, you can’t see its disk, but you can see the star that’s captured astronomers’ imaginations!
