Bad Astronomy: Misconceptions and Misuses Revealed, from ...

HUBBLE TROUBLE 233
also used to say that Hubble can’t take images of the Moon. It’s
not that the Moon is too bright, it’s that it moves too fast. Hubble
must be maneuverable enough to track nearby planets as they
orbit the Sun, but the Moon moves across the sky much faster
than even the fastest planet. There’s no way, I would say, that it
could track the Moon.
I was partially wrong in saying that. True, Hubble cannot track
the Moon. But it doesn’t have to track it. The Moon is bright.
When you take an image of a bright object, you can take a shorter
exposure. In fact, Hubble could take an image of the Moon with
such a short exposure time that it would look as if the Moon were
not moving at all. It’s just like taking a picture out the window of
a moving car. If you take a long exposure the trees will look
blurred due to your motion. But if you snap a fast one the trees
will look sharp and motionless. They don’t have time to blur.
In 1999 just such an image of the Moon was taken by Hubble.
The astronomers were clever. They put Hubble into “ambush
mode,” pointing it to a place where they knew the Moon would be
and waiting for it to move into view. When it did, they took the
image using a fast exposure. The results were pretty neat. They got
nice pictures of the Moon, although not really any better than we
had from orbiters. The principal goal of the observations was to
get spectra of the lunar surface to help astronomers understand the
properties of all the planets, and the images were an added bonus.
So Hubble can indeed shoot the Moon, and did in the waning
years of the twentieth century.
Ironically, while many people think that the Moon is too bright
to observe with Hubble, it’s the very brightness that allows Hubble
to observe it! It’s bright enough to let us take short snapshots of it
without blurring.
TURNING THE CRANK
Unfortunately, the Moon issue won’t die. Some people really want
to see conspiracies and cover-ups everywhere they look, even when
there are none to be had. One such person is Richard Hoagland,
who maintains a long list of supposed NASA shenanigans, most of