PDS 70b: A Newly Formed Planet?

A team of astronomers recently announced the discovery of PDS 70b, the first planet known to orbit the star PDS 70 (AKA V1032 Centauri). But what did the team actually find?

PDS 70 is a T Tauri variable star. For decades, astronomers generally have thought that T Tauri stars have formed recently. Therefore, most astronomers consider PDS 70 to be a very young star. Observations published in 1992 suggested that there might be a disk of dust and gas orbiting PDS 70 (the technical term for a disk around a star is a circumstellar disk). This was confirmed in 2006. Circumstellar disks around young stars are thought to be protoplanetary disks, that is, disks of material out of which planets form.

In 2012, a gap was found in the disk surrounding PDS 70. This gap was attributed to the presence of a forming planet that was robbing matter from that portion of the disk. It was this expectation that prompted the team of astronomers to use the best instruments available for follow-up work. They found a knot of bright material in the gap, which they interpreted as being the expected planet forming in the gap.

Notice that there is much theory-laden interpretation in this finding. The star PDS 70 is assumed to be very young, its circumstellar disk is assumed to be a protoplanetary disk, the gap in the disk is assumed to be caused by a forming planet, and the knot in this gap is assumed to be that forming planet. All these assumptions may be correct, in which case the conclusion may be correct. But more to the point, why do astronomers generally think that this is a forming planet? Because it conforms to their theory of how planets form. But there is no direct evidence that this is a forming planet. It is possible that PDS 70b is a fully formed planet. While this work is consistent with the naturalistic theory of how planets form, it doesn’t prove that the theory is correct.

What if it turns out that PDS 70b is a very young planet? Biblical creationists believe that the world is young, so it ought not to be a surprise that there are very young stars and planets.