In sci.astro message , Fri,
18 Feb 2011 20:05:14, Sam Wormley posted:

On 2/18/11 5:20 PM, Dr J R Stockton wrote:
With an assumed mass of 4 Jupiters, such a planet would be very easy to
detect given 19th century (or earlier) technology and sufficient
patience. It will displace the barycentre of the solar system
periodically by of the order of 250 AU, and Sun and Earth both orbit
that barycentre. That will easily be detected by parallax measurements
of many of the nearer stars, assumed to be on the average fixed.
Unfortunately, the orbital period is of the order of 1.8 M years.

Jupiter at a distance of ~ 5AU has a much greater effect on the Sun
than would a 4 Jupiter-mass planet beyond the Kuiper belt.

Your ignorance is indeed profound.

The force on the Sun from Jupiter is indeed much greater than that from
the supposed Tyche. But Jupiter is a flighty thing, and pulls in the
opposite direction after only 6 years; it takes Tyche nearly a million
years to do that. If there is a school near you with a competent
physics teacher, ask for the definition, and an elementary explanation
of, barycentre.

The further away from the Sun an orbiting object is, the bigger its
effect on the distance of the Sun from the barycentre - and the longer
they take to move around it.

--
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