gnome is a meta-package that brings in the full Gnome desktop environment which includes many, many things:
$ apt-cache show gnome
[ ... ]
Description-en: Full GNOME Desktop Environment, with extra components
This is the GNOME Desktop environment, an intuitive and attractive
desktop, with extra components.
This meta-package depends on the standard distribution of the GNOME
desktop environment, plus a complete range of plugins and other
applications integrating with GNOME and Debian, providing the best
possible environment to date.
What you're after is probably the
$ apt-cache show gnome-core
[ ... ]
Description-en: GNOME Desktop Environment -- essential components
These are the core components of the GNOME Desktop environment, an
intuitive and attractive desktop.
This meta-package depends on a basic set of programs, including a file
manager, an image viewer, a web browser, a video player and other
It contains the official “core” modules of the GNOME desktop.
As a general rule, you should always use
apt-cache show PACKAGENAME before installing to make sure you know what the package is.