Jonathan Silverlight wrote:

In message , Ron Baalke
writes

The Keck Interferometer observations revealed a gap of 18
million miles between DG Tau and its orbiting dust disc.
Akeson notes that of the extra-solar planets - planets
orbiting other stars - discovered so far, roughly one in four
lies within 10 million miles of the parent star. Since
planets are believed to form within a dust disc, either DG
Tau's disc has a larger-than-usual gap, or the close-in
planets form farther from the star and migrate inward.

I don't begin to follow that. Are they saying that three in four lie
more than 10 million miles from their star, like the planets in our
solar system? Then they are in the majority, and DG Tau is normal.

It appears that they have taken into account the fact that the
extrasolar planets discovered so far are all giants, and all
the giant planets in our Solar System are much, much farther
than 10 million miles from the Sun. With a gap of 18 million
miles, the closest that a giant planet could form might be
something like 25 million miles from its star.

I'm slowly beginning to accept the possibilty that planets
migrate inward, and comets are flung outward. I have always
believed that the planets formed about where they are now, and
the comets formed in the Oort Cloud. I'm not yet convinced
that that is not so, but I'm headed in that direction.

-- Jeff, in Minneapolis

Oh, by the way: Your mother saw a hamster.

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