The article was originally published at The Conversation.
Peter Tuthill is an Astrophysicist at the University of Sydney.
A research fellow at the University of Sydney is named Barnaby Norris.
How do planets form? Scientists used to think they understood the process by studying our own solar system.
The discovery of planets around distant stars in the 1990s made it clear that the picture was much more complicated than we knew.
A hot Jupiter-like gas giant has been spotted in the process of forming around a star about 500 light-years from Earth.
This rare babysnap of a planet in the process of forming, drawing down matter from a vast disk of dust and gas swirling around its also-infant sun has opened a window on mysteries that have puzzled astronomy for years.
10 super extreme exoplanets are out of this world.
Scientific inquiry into the origins of Earth and the other planets of our solar system began in the 1700s.
The sun and its little planetary family all grew from a large rotating primordial cloud, as proposed by the German philosopher Immanuel Kant.
This idea was refined by the French polymath Pierre Laplace, and has had many more additions and revisions, but modern scientists think it was on the right track. Most of the observed features of our solar system can be explained by the modern descendant of the hypothesis of Kant.
A beautiful digital replica of our solar system will emerge from the simulations we can now run with all the right settings. It will have the right kinds of planets in the right order, just like the real thing.
The model seemed to have the bases covered, as it was a triumphant synthesis of threads from geology, chemistry, physics and astronomy. Astronomers confronted it with planets from outside our solar system.
There was controversy when the first systems of planets were discovered. The rest of the universe didn't fit the model at all, because the new planets didn't care about what happened around our little sun.
There is a realization that there may be different pathways to form a planetary system. Our sun's family of planets is starting to look a bit odd, as thousands of planets surround other stars.
Despite this, one of the most basic physical components of the planet-building machinery we believe is responsible for forming giant gassy planets like Jupiter and Saturn has stood the test of time.
The gases and dust grains are thought to comprise the primordial cloud, which is shaped like a spinning disk with the infant star in the center. Dust grains clump together into successively bigger grains, then pebbles, rocks and on up in a cascade to baby planets.
The tipping point for such a clump is when it gets big enough. The attraction of gravity helps the planet quickly draw in gas, dust and other clumps, clearing its path and carving a circular gap in the disk.
It is one of the signature successes of modern astronomy that the theories of disk gaps are now seen and studied in the universe.
There are some things core accretion cannot explain. Massive planets are out in the cold distant reaches.
The core accretion theory states that planets shouldn't exist. They are too far out to run the business of planet-building.
A new model was formulated to explain the huge distant planets. The idea is that if the primordial disk has enough mass, it can become unstable and collapse in a big crunch.
This new picture seemed like it could explain the outlier planets, but since all known examples were very old, this theory has remained. Until now.
We spotted a massive planet around a star 500 light-years from Earth last year.
The star, namedAB Aurigae, has become famous in astronomy circles for its beautiful spiral disk.
The clumps and waves seen in this disk are consistent with what one might see if there was a collapse. There was no evidence of a forming planet.
The planet is embedded in a thick, swirling halo of dust and gas, which is indicative of the collapse of the universe. The planet is so far away from its star that the traditional core-accretion theory could not explain its formation.
There is strong evidence for the alternative theory of collapse.
The discovery was made using observations from both the Hubble Space Telescope and the Subaru Telescope.
The planet is hot enough to light up around 2000 degrees Celsius. The glow gives away the presence of the planet. The blue light of the central star illuminates the swirling gas and dust around the forming planet.
The case is not closed despite the new discovery providing a critical piece of the puzzle.
As our telescopes get bigger and our methods get more advanced, we expect to see many more forming planets caught at all stages of their development, as well as fully formed mature planets like Earth.
We can hope to answer some of the big questions, such as how did such a weird and diverse range of planetary systems form across the galaxy, what are the conditions like on these new worlds, and how does our own little solar system fit in among them.
This article is free under a Creative Commons license. The original article can be found in the new tab.
Follow all of the Expert Voices issues and debates and become a part of the discussion on social media. The author's views are not necessarily those of the publisher.
All Rights Reserved © 2024
