netscape version number

Dear Sir,
When I use navigator.userAgent property, in microsoft internet explorer, I get MSIE somewhere in the text.
But under netscape, I don't get Netscape word anywhere.
Instead I get:
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.9) Gecko/2009040821 Firefox/3.0.9
Then how to find out the version number?

Thank you sir, what is the difference between netscape, mozilla, firefox?

Hi Gopinath,

Mozilla/5.0 is the version number of browser.