Make sure you have xargs, head, and mplayer installed (via your package manager) and run:
/usr/bin/curl http://www.nasa.gov/ram/35037main_portal.ram | /usr/bin/head -1 | /usr/bin/xargs mplayer
If the URL above changes, look for the ‘RealPlayer’ option at http://www.nasa.gov/ntv for a new .ram file.