AP: First detection of extra-solar terrestial sized planet?

An average nine year old could add up those sums.
Peter.

An average nine year old could add up those sums.
Peter.

Absolutely! But not journalists...

I did a blog entry on yesterdays Irish Times coverage of it:

blog.scealnetworks.com/astronomy/gliese-581c-discovery.html

As pointed out by Greg Lauglin of UCO Lick, most of the media show the Artists impression,which is misleading: detailed in what we don't know (planet surface, if it has one), and wrong in what we do know: star colour, size in comparison to e.g. Gl 581b.

The mass is almost certainly an underestimate, as its done by radial velocity; as the
discovery paper points out, its M sin i, where i is the inclination. However we don't
know the inclination. It would only be 5 Earth masses if the planet was in direct alignment
with us. This is unlikely as if it was, both it and Gl 581b (discovered in 2005) would
probably have been spotted by transit already. (See transitsearch.org ).

However if anyone wants to answer these questions, there is a transit due on May 7.
Gl 581 is magnitude 10.6 in the visible, should be doable with equipment some people
have around here. Unfortunately that transit is at 17 UTC; perhaps booking a flight
to Tahiti is in order?

- Alastair

Anyone got a photomultiplier or decent CCD

Theres' a transit opportunity tonight with Gliese 581,
the home of 581c. Its big neighbour 581b transits tonight at 22:43 UT.

blog.scealnetworks.com/astronomy/gliese-...transit-tonight.html

A transit from it would tell us the inclination of the planets, and
their real masses.

Do you know an approximate micro variability of GL 581. ie. is it +/-.001 mag? Do you have a precise timing of start time and finish.
The attempt to detect the transit will depend on transparency of the sky.
I see that there has never been a transit detected photometrically or mass determined. I appreciate the significance of attempting this observation.

I'll plan to attempt to record the transit this evening.
I have never attempted anything like this before. It appears to be very challenging.

Eamonn A

From the Gl 581c discovery paper:

Gl 581 has been classified as a variable star (HO Lib).
However, the data which have led to this classification (Weis,
1994) have a short-term variability of ∼ 0.006 mag. The vari-
ability quoted by the author is marginally above the errors bars
and, if real, has most likely a long-term nature (several years).

Ref: Weis, E. W. 1994, AJ, 197, 1135

With a predicted transit time of 84 minutes (from the link to UCO Lick in
my blog page).

It would be interesting to know how you get on. Good luck.