<p><hr><hr><p>
<center>
PLANETARY MIGRATION
</center><p>
Before the onslaught of the extra-Solar planets, the party 
line was that planets formed at
particular radii in the Solar Nebula and essentially spent 
their lives at around the same
distance from the Sun. This position is no longer held by most people.  The 
<font color=magenta><i>snowline</i></font> in our
planet forming disk is around 3-4 AU and it was expected 
that all Jovian planets in extra-Solar
planetary systems would be found outside the 
<font color=magenta><i>snowlines</i></font> of their 
disks. The discovery of so-many Jupiter-like 
planets close to their stars, inside the 
<font color=magenta><i>snowlines, 
suggested that planets likely migrate around their systems over 
their lifetimes</i></font>.
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<td><center><a href="https://www.youtube.com/watch?v=BiIh_r-KTGM">
<img width=525 src="planetmigration.jpg"></a>
<a href="https://phys.org/news/2016-05-exoplanets-complex-orbital-planetary-migration.html">
<img width=400 src="223kepler.jpg"></a>223 Kepler</center></td></tr>
<tr><td><img src="cosmology-9.jpg"></td>
</tr>
</table>
</center>