problems with installing the rails gem

hello

i tried to install he rails gem

$gem install rails

and got the error messege

unable to download data from http://rubygems.org/ -ssl_connet returned

=1 errno =0 state =sslv3 read server certificate b: certificate verify failed

(https:/api.rubygems.org/latest_specs.4.8.gz

what sholud i do to fix that??

asaf