I am beginning to learn how to take pictures of the night sky in various ways.
1) Mounting the camera on a tripod (good for making star trails)
2) Mounting the camera on the outside of the telescope (called "piggybacking" - that's how this back ground photo was made)
3) Mounting the camera so that it looks into the same eyepiece that I would look into (called "eyepiece projection")
4) Mounting the camera directly on the telescope, so the telescope is
essentially a 3000 mm telephoto lens (called "prime focus
astrophotography")
Examples of each of these types of photography are shown below. They aren't world-class, but I'm learning, and I'm having fun!
Equipment:
Telescope: Meade 12" LX90 GPS (currently on a fork mount in alt-az mode)
Camera: For eyepiece projection I'm using a Canon PowerShot A720 IS.
For all other methods, I'm using a Canon Rebel XS (EOS 1000D)
M 57, the Ring Nebula, in Lyra, the Lyre
This
is probably the most famous example of a Planetary Nebula in the sky.
It is the visible remains of a star, similar to our Sun, that has run
out of fuel and blown off its outer layers, leaving behind a white
dwarf star in the center. What you are seeing is the gas blown away
from the star. It only takes about 50,000 years (the blink of an eye,
astronomically speaking) for the shell of gas to expand so much that it
will fade from view.
Single exposure, prime focus, 90 sec, ISO 800
M20, the Trifid Nebula, in Sagittarius, the Archer
This
is a very different type of nebula, one in which stars are being born,
not dying. Patches of this cloud of gas and dust are collapsing under
their own weight, forming new stars. Those stars burn very hot, causing
the remaining cloud to glow (the red parts) and reflect the star's
light (the blue parts). This image is very faint because my telescope
is not properly aligned with the Earth's rotation axis (that will cost
more than I have to spend), so I have to keep the exposures short so
the image doesn't streak.
Single exposure, prime focus, 90 sec, ISO 800
Double star: Albireo, in Cygnus, the Swan
Over
half of the stars we see in the night sky are actually two or more
stars obiting around each other. Many of them are too close to each
other to be seen as two distinct stars in our telescopes. though
astronomers have other ways of detecting a double. Here is one of the
most magnificent examples of a double star. It is easily resolved (seen
as two stars) in any telescope, even good binoculars held very steady.
It's also very popular because of the color contrast between the two -
one is yellow and the other bluish-white.. The color is determined by
the surface temperature of the star: red is the coolest, then yellow,
white, and blue is the hottest.
Single exposure, prime focus, 10 sec, ISO 400
Double star: eta Cassiopeia, in Cassiopeia, the Queen
Some double
stars are much closer together, and become a bit of a challenge to
resolve (separate). You can also see that there is again a color
contrast between the stars, though not quite so vivid as with Albireo.
Single exposure, prime focus, 2 sec, ISO 400
Double star - Mizar and Alcor, in Ursa Major, the Big Bear
The
star in the middle of the handle of the Big Dipper is called Mizar. If
you have good eyes and you look carefully, you can see another,
fainter, star nearby called Alcor. They are what is called an "optical
double", meaning they are not actually orbiting each other, but instead
just happen to lie along the same line of sight from Earth.
Interestingly, though, Mizar turns out to be a true double star, as you
can see through almost any telescope. Even more interesting, Both stars
in Mizar turn out to be doubles themselves, as shown by spectroscopy -
it's a 4-star system! In the photo below, Mizar is at
the bottom, Alcor is at the top.
Single exposure, prime focus, 0.6 sec, ISO 400
Double star - nu Corona Borealis, in Corona Borealis, the Northern Crown
One
more double star. This one shows very little color contrast, but it's
still interesting because of the color and distance between the stars.
They are very far apart, so easily resolved in any telescope or
binoculars. And they are a distinctive orange color. A very pretty
sight.
Single exposure, prime focus, 1 sec, ISO 400
Jupiter and two of its moons
This was a lucky evening. I
didn't know it, but the shadow of one of Jupiter's Galilean moons (Io)
was crossing the face of the planet. I managed to capture two of the
moons along with the shadow. These types of events are very common - a
moon's shadow crosses the face of Jupiter about once every day. For it
to happen in the evening while Jupiter is photographable is a bit more
rare - maybe once or twice per week on average. The passage generally
takes a few hours, plenty of time to watch by eye and photograph it!
13 images stacked, eyepiece projection, 1/400 - 1/100 sec, ISO 200
More to come...
