JWST will be able to see right through and into massive clouds of dust that are opaque to visible-light observatories like Hubble, where stars and planetary systems are being born.
What's Inside Those Clouds of Dust?
Here's a famous nebula, the Pillars of Creation, as captured by the Hubble Space Telescope:
Eagle Nebula, Pillars of Creation. Credit: NASA/ESA/Hubble Heritage
Team (STScI/AURA)/J. Hester, P. Scowen (Arizona State U.)
While this image is spectacular, there are actually stars that Hubble can't see inside those pillars of dust. And that's because the visible light emitted by those stars is being obscured by the dust. But what if we used a telescope sensitive to infrared light to look at this nebula?
Here is another Hubble view, but this time in near-infrared:
Infrared Eagle Nebula, Pillars of Creation. Credit: NASA, ESA,
and the Hubble Heritage Team (STScI/AURA)
In the infrared more structure within the dust clouds is revealed and hidden stars have now become apparent. (And if Hubble, which is optimized for visible light, can capture a near-infrared image like this, imagine what JWST, which is optimized for near-infrared and 100x more powerful than Hubble, will do!)
Here is another nebula, the "Mystic Mountains" of the Carina Nebula, shown in two Hubble images, one in infrared (right) and one in visible (left) light:
Credit:NASA/ESA/M. Livio & Hubble 20th Anniversary Team (STScI)
More stars are visible that weren't before.
How Does This Work?
We can try a thought experiment. What if you were to put your arm into a garbage bag?
Your arm is hidden. Invisible.
But what if you looked at your arm and the garbage bag with an infrared camera? Remember that infrared light is essentially heat. And that while your eyes may not be able to pick up the warmth of your arm underneath the cooler plastic of the bag, an infrared camera can. An infrared camera can see right through the bag!
And this is how the infrared telescope works as well. It sees the heat or infrared light being emitted by the stars within the cooler dust clouds.
Here's one more - the gorgeous Horsehead Nebula:
And the recently released Hubble image showing the Horsehead in infrared light:
Credit: NASA/Space Telescope Science Institute (STScI)
JWST's amazing imaging and spectroscopy capabilities will allow us to study stars as they are forming in their dusty cocoons. Additionally, it will be able to image disks of heated material around these young stars, which can indicate the beginnings of planetary systems, and study organic molecules that are important for life to develop.
ALMA image of the young star HL Tau and its protoplanetary disk. This best image ever of planet formation reveals multiple rings and gaps that herald the presence of emerging planets as they sweep their orbits clear of dust and gas. Credit: ALMA (NRAO/ESO/NAOJ); C. Brogan, B. Saxton (NRAO/AUI/NSF)
This video shows how JWST will peer inside dusty knots where the youngest stars and planets are forming