Brilliant! It was only a matter of time before they could detect the Earth sized planets. Far sooner than I thought they would actually. 'C' huh? Uhh OK
(or whatever number it is) whatever happened calling things names?
Who gets to decide?
I'd be pretty boring if all our modern day discoveries were just numbers.

According the The Times, the fasted manned spacecraft (Apollo 10) travelled at 24,791 mph (11.08 km/s).

Presumably it travelled faster at take off to reach escape velocity. And presumably the Times refer to a sustained velocity.

Apollo 13 clearly finished its journey doing precisely 0 mph.

Brilliant! It was only a matter of time before they could detect the Earth sized planets. Far sooner than I thought they would actually. 'C' huh? Uhh OK
(or whatever number it is) whatever happened calling things names?
Who gets to decide?
I'd be pretty boring if all our modern day discoveries were just numbers.

I'd vote for "Bob"

Brilliant! It was only a matter of time before they could detect the Earth sized planets. Far sooner than I thought they would actually. 'C' huh? Uhh OK
(or whatever number it is) whatever happened calling things names?
Who gets to decide?
I'd be pretty boring if all our modern day discoveries were just numbers.

I'd vote for "Bob"

Reminds me of the 1999 movie "Armageddon" when the hick hillbilly astronomer discovers the asteroid that would eventually be the mother of all asteroids. This is when he gets his discovery confirmed and he is on the phone (presumably with someone at the Minor Planet Centre? )

Hick: "The guy who finds it gets to name it, right?"
MPC: "Uh... yeah."
Hick: "I'd like to name it after my wife, Vera." (She looks at him with happy astonishment.) "....She's an evil, life-destroying bitch from whom there is no escape!"

Classic!

So we are all agreed that manned Apollo 10 would have reached that planet in 124,909 years.

Not 5 billion.

Peter.

Bob is goood....
but I like 'Alan'.

(although I think Homer Simpson has already named a constellation that)

Ok Ok....amm....
How about.,..

'Longulus'

from the Latin dictionary: [rather long, rather far, at a little distance]
As in,

'' Captain! We are recieving a distress call from outpost 581 c on Longulus!
It looks like the IFAS imperium have launched an attack on the Longuloids...
something about....Amateurs..... getting their ....own back?....
The signal is garbled Sir!''

Captain;
''Set course for the Longulus system. Warp factor 9.....ENGAGE!''




:wink:

I'd call it "Pluto".

Then we can say "Pluto is a planet".

Peter.

So we are all agreed that manned Apollo 10 would have reached that planet in 124,909 years.

Not 5 billion.

Peter.

I'm sure your agreed with yourself Peter. Rather presumptious to add the rest of us into your agreement...

Of course, the 5 billion years comes from The Times [1] - perhaps you could do the maths for us all and put us (and The Times) out of our misery [2]

Then again, perhaps not. Judging by your figures for Voyager reaching Alpha Centauri (4 light years?) in 80,000 years and Apollo doing the same trip in 123,726 years, I'm not sure how you then get Apollo reaching Gliese 581c in 124,909 years (a mere 1183 years to travel an extra 16.5 light years)...

Dave

[1] Quote: "It would take the fastest manned spacecraft, Apollo 10, 4.86 billion years to get there, travelling at 24, 791mph"

[2] By my calculations, its a tad over half a million years. Never trust what you read in the papers.

Its a pity it does not transit the star then we could get some more info. As for a name.... ICUDOUCUS.

A few years ago Leo Enright gave a lecture where he mentioned astronomers had detected a heavily laden sodium atmosphere around an extra-solar planet.

I quipped, "Congratulations! We've just found the most heavily-light polluted planet in the Universe!"

Wouldn't be interesting to get its light into a spectrograph and see what its atmosphere contains. !
Its life Jim, but not as we know it

I AGREE!. I calculated for Alpha Centauri.(80,00 years for Voyager.)

Not the new planet almost four times farther away.

Apollo 10 would indeed reach the new planet in about half a million years.

I spotted my mistake the second I sent it and waited for the flak!

Peter.

I spotted my mistake the second I sent it and waited for the flak!

And some flak you got!

I also spotted my mistake when I said it was "four times farther away".

It's almost five times farther away!

So around 625K years would be correct!

Peter.

P.S. The great admit their errors.

Your not the only one making errors. I was watching the TV3 New last night and if I'm not mistaken they said the planet was 2 million Light Years away . Just shows you can't beleve everything they say on TV.

Martin Turner had a brilliant cartoon about it in the Irish Times today.

A few atronomers peering at it through an enormous scope wondering if the water was pure enough for Galway.

Peter

If anyone is interested.... The Times (British) quoted a 5 billion year journey time to Gliese 581c. Clearly something wasn't quite right with the mathhs.

Gliese 581 is about 120 trillion miles away (120,519,500,000,000 miles). The fastest manned spacecraft (sustained speed) is Apollo 10 at 24,791mph.

What the Times did was divided the distance by the speed (120 trillion/25,000) and got 5 billion - *hours*. Unfortunately, they forgot to reduce the time to years....

5 billion/24*365 is just over half a million years.

So, a lesson in making sure the papers (and the TV) have got their maths right...

Cheers
Dave

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.

I presume the short term variability is a long one, that it won't be picked up during 'b's transit and be lost in the noise.

In the case of 'b', I'm guessing that the eclipse may block approximately 1/300th the star's surface, dimming its light by only 0.003 magnitude, or 0.3%. This all depends of course on the ratio diameter of 'b' to the star. An eclipse of this degree cannot be detected unless the photometric measurements have a consistency approaching the milli-mag level over a span of many images (ie. 0.001 magnitude variation means that the brightness variation is about 0.1% of the signal).

What is the ratio of 'b' to star?
What exposure should I apply? eg. 5 to 40 seconds?
I wonder how precise the predictions are? I may have to start earlier this evening, in case the transit starts earlier than anticipated.

Detecting the transit is going to be an extremely difficult challenge. This will require luck of timing to catch an eclipse, the acquiring high quality image data, and the application of sophisticated techniques for image processing and measurement. Going to be a tall order to pull off.

Eamonn A

I'm going to watch this thread with great interest as this is exactly the sort of thing I want to try when I get myself finally set up. I imagine that the chances of getting enough reliable data for generate a light curve are vanishingly small given all the different factors and variables you have to wrangle with, but if you pull it off it will be an enormous feather in your cap! What instruments are you guys planning to use for the observations?

Phil.