The launch of the Herschel and Planck spacecraft is scheduled for 13:12 GMT (9:12 EDT) this morning (Thursday). You can watch it live, starting at 12:40 GMT (8:40 EDT) at this link.
The two spacecraft are launching together in what was originally a cost saving move, but the complexity of preparing two spacecraft at once has caused frequent delays and cost overruns. However, now that launch day is here, hopefully the cutting-edge technologies included in both spacecraft will soon pay off in new discoveries astronomy and cosmology. Read more about the two spacecraft here.
Also, Robert Simpson at Orbiting Frog has some interactive features that show the altitude, velocity and acceleration of the Ariane rocket as it progress through the air into space. You can even click and drag to zoom in on a section of these charts, and move your mouse around inside them to get more information.
And the first of five spacewalks for the Hubble Space Telescope servicing mission starts at around 9:00 am EDT, and will be pretty much an all-day event. Watch live on NASA TV.