21 September 2011
Take a few moments to take in all of the wonderful details captured in this new photo of some baby stars in a glowing cloud of gas. Have you looked closely and seen everything? Actually, this is a trick question, because there are invisible objects hiding in this photo!
Do you see the black marks in the top-right corner of the picture? Here, the gas cloud hasn’t been photographed because there are dark clouds called ‘Bok Globules’ blocking the view. These Bok Globules absorb light from the bright cloud of gas behind it, creating the illusion that there is nothing there.
Like the baby stars that we can see shining brightly in this image, the Bok Globules also have newborn stars hiding inside. But the densely packed dust and gas inside the Bok Globules acts like an invisibility cloak for these stars.
This invisibility cloak, though, has a weakness: It fails when astronomers look at the Bok Globules using a special type of telescope that detects infrared light. Our eyes can´t see infrared light, but we use it at home to switch on the TV with a remote control. And infrared light can also travel through the dust inside Bok Globules.
So, despite their best efforts to keep some stars secret, the Bok Globule’s cloaking device is no match for astronomers’ range of powerful telescopes!
Cool fact: The astronomer called Bart Bok, who discovered Bok Globules in the 1940s, thought that stars might be born inside these dark clouds. But it took nearly 50 years for his idea to be proved right using infrared telescopes!