SoHO (Solar and Heliospheric
Observatory) was launched in December
1995 in an orbit around the first Lagrange point. This is a point directly
between the Earth and the Sun where the gravitation forces balance such
that SoHO always stays between them. This point is about 1% of the distance
to the Sun, about 1,000,000 miles, four times further away than the Moon.
The SoHO orbit
at the L1 point.
Trace (Transition Region
And
Coronal
Exploror)
was
launched
in April 1998 on a Pegasus XL rocket.