I've only cooked them when they were yellow. What is the length of this squash?

Here is a link that might be useful: Spaghetti squash

No sorry it is still far too green. You can cook it and try it if you wish but you won't care for the flavor at all IME. It will have a sharp, unripe flavor not at all like spaghetti squash normally tastes.

Spaghetti is a winter squash harvested in fall in late Sept. or October when the vine is mostly dead and the squash itself has a hard rind and are a bright solid golden yellow.

Dave

Here is a link that might be useful: How to grow and harvest winter squash

Here's a pic from another angle. Two sides are golden, two sides green. It is 9" long and 18" around. I was afraid it wasn't ready :-( And I was trying so hard to save this plant to let this one squash ripen. The rest of the plant took a hit from powdery mildew. Grrrrrr.......

Look at the pics in the link I provided above. Your squash is approx. another 2 months or more from being ready and will still be fairly green inside as well.

Sorry.

Dave

I know this was asked a long time ago, but this also happened to me. It was not good to make spaghetti squash at all, so I cut it up and took all the seeds out and cooked it in a small amount of water. I added molasses and a stick of cinnamon and it was actually pretty good. Way better than letting it go to waste. :)

marbella ...I agree. spaghetti squash, when mature just develops more texture an has slightly less water contents. it is similr to other squash types called SHARK FIN and COYOTE(?). The latter is sold at Asian markets when quite young. It is often is substituted for SHARK FIN squash in summer. I have made shark fin (faux) soup with it many time.

I'd like to know if a spaghetti squash is supposed to have a lot of seeds when it's ripe. I just cut open a yellow one that looked ripe on the vine and it had very few seeds.

Yes it normally has a quite large seed cavity filled with seeds if mature. If there were only a few then it was likely not mature and ready for harvest yet. Was the stem on it hard, dry and brown? The cavity in the pic is full of hundreds of seeds.

Dave