This spot is called the Earth-Sun L2 point, the second of five
"Lagrangian Points" named for Joseph-Louis Lagrange (1736-1813) who
calculated their existence.
In practice, a spaceship is actually more stable orbiting around the L2 point
than trying to remain at the precise point. But the effect remains the same.
Wherever earth happens to be in its annual path around the Sun, an L2 spacecraft
would be positioned a million miles above the night side of the planet. And with
the Sun and the Earth at its back, a telescope aboard the spacecraft would always
have a clear, uninterrupted view outward into the Universe.
More on Lagrange Points...