Imagine being William Herschel and looking through your monstrously big 40-foot telescope in November 1787 and seeing this faint shape appear. An actual space bubble thingy! Those were the days of pioneering explorations indeed.
But how big is this bubble, you ask?
Hold onto your cold space beer because it's currently about 7 light-years across! To put that into perspective, it's like your "Knock, knock" zooming through the Bubble at the speed of light for 7 straight years just to reach the other side of this magnificent sphere and waiting another 7 years to hear "Who's there?". Your baby will have left the house before you'll hear the full joke ;-)
So what exactly is this bubble and surrounding region made of?
While the colors (arguably) make for a nice display they also reveal the composition. Emissions can easily be measured to reveal exactly what particular elements do the emitting; the blue in the image shows emission from hotter oxygen gas, while the various red hues combine to show the emissions from warm hydrogen and nitrogen gases. Light is so rich in information!
Looking for a nice vacation destination?
The travel time might put you off... the Bubble Nebula is approximately 7,100 light-years away from us here on Earth. So the light hitting my telescope left there when the first signs of civilization (that we found) started to take shape on Earth! We've changed considerably since then, multiple empires rose and fell, who knows what has changed over there?
Now, here's the coolest part!
The Bubble Nebula is not just a static feature in the sky; it's actually the result of the relentless pounding of intense radiation of one particularly active star, continually expanding the bubble at the rate of about 6.5 million kilometers per hour! The bubble has increased in diameter by more than thirteen quadrillion kilometers since it was discovered and is not slowing down! As mind boggling as this is (they might just as well called it 13 Fantastillion kilometers), that's still about 0.6% the speed of light...
So, the next time you gaze up at the night sky, think of the Bubble Nebula, its ever-expanding presence as a testament to the wonders of the universe. And yes, the eight-year old is right.
All things considered, it's a starfart.