Pulsar timing can be used to weigh the mass of the planets in ourSolar system

SPACE.com -- Spinning Stars Help Scientists 'Weigh' Our Sun's Planets
"The method developed by Champion and his colleagues, is based on
corrections that astronomers make to the regular radio wave "blips" that
come from distant pulsars.

As the Earth travels around the sun, that movement affects the time it
takes for pulsar signals to arrive at our planet. In order to get around
this effect, astronomers instead calculate when the pulses would have
arrived at the solar system's center of mass.

This point, called the barycenter, is the rotation center for all the
planets. Since the arrangement of the planets around the sun changes
over time, the barycenter also changes relative to the sun.

To locate the barycenter, astronomers use both a table with the
positions of the planets in the sky (called an ephemeris) and the values
for the planetary masses that have already been measured. "
http://www.space.com/scienceastronom...rs-100823.html

Dear Yousuf Khan:

On Aug 23, 12:09*pm, Yousuf Khan wrote:
SPACE.com -- Spinning Stars Help Scientists 'Weigh'
Our Sun's Planets "The method developed by Champion
and his colleagues, is based on corrections that
astronomers make to the regular radio wave "blips" that
come from distant pulsars.

Similar to Kopeikin's "speed of gravity" experiment...

As the Earth travels around the sun, that movement
affects the time it takes for pulsar signals to arrive at
our planet. In order to get around this effect,
astronomers instead calculate when the pulses would
have arrived at the solar system's center of mass.

This point, called the barycenter, is the rotation
center for all the planets. Since the arrangement of
the planets around the sun changes over time, the
barycenter also changes relative to the sun.

To locate the barycenter, astronomers use both a
table with the positions of the planets in the sky
(called an ephemeris) and the values for the planetary
masses that have already been measured. "
http://www.space.com/scienceastronom...stem-planets-p...

I would think this method would allow us to detect anomalous
distributions of Dark Matter, at least within Jupiter or Saturn's
orbit, anyway... maybe even explore for sources of the Pioneer Anomaly
over that same terrain...

David A. Smith

On Aug 23, 3:09*pm, Yousuf Khan wrote:
SPACE.com -- Spinning Stars Help Scientists 'Weigh' Our Sun's Planets
"The method developed by Champion and his colleagues, is based on
corrections that astronomers make to the regular radio wave "blips" that
come from distant pulsars.

As the Earth travels around the sun, that movement affects the time it
takes for pulsar signals to arrive at our planet. In order to get around
this effect, astronomers instead calculate when the pulses would have
arrived at the solar system's center of mass.

This point, called the barycenter, is the rotation center for all the
planets. Since the arrangement of the planets around the sun changes
over time, the barycenter also changes relative to the sun.

To locate the barycenter, astronomers use both a table with the
positions of the planets in the sky (called an ephemeris) and the values
for the planetary masses that have already been measured. "http://www.space.com/scienceastronomy/weighing-solar-system-planets-p...

I don't think so. It does tell how fast a neutron star is spinning,or
if its part of a twin system. TreBert

On 23/08/2010 3:39 PM, dlzc wrote:
I would think this method would allow us to detect anomalous
distributions of Dark Matter, at least within Jupiter or Saturn's
orbit, anyway... maybe even explore for sources of the Pioneer Anomaly
over that same terrain...

David A. Smith

Well, if we can weigh the entire solar system in one fell swoop, then
when we subtract that number minus the mass of the planets and the Sun
as we know them, then we'll arrive at a number that gives us the weight
of the Planet X, Nemesis.

Yousuf Khan

In article ,
dlzc writes:
http://www.space.com/scienceastronom...stem-planets-p...

I would think this method would allow us to detect anomalous
distributions of Dark Matter, at least within Jupiter or Saturn's
orbit,

I'd expect just timing the orbits of the planets would give a better
result. Essentially, each planetary period gives a value of GM,
where M is the mass inside the planet's orbit. If GM for outer
planets is larger than for inner ones (after accounting for known
objects), it would be evidence for dark matter. I am pretty sure we
would have heard about such evidence if it existed :-), but I don't
know what the limits are.

It might be instructive to calculate the expected amount of dark
matter within, say, the orbit of Neptune.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA