The Constellation Gemini, Photographed with an iPhone (2018)
Here are some photos of the constellation Gemini, and
neighboring stars, taken with an iPhone, in the spring of 2018 from Edmonton
Alberta (latitude 54). The pictures have
been enhanced via the Gimp colour filter for brightness and contrast, increasing
both brightness and contrast to bring out the less bright stars. The accompanying picture is an inverted
version of the first, swapping bright pixels for dark, as it can be easier to
see some of the more subtle stars that way.
From a bright city sky, you can’t necessarily make out many
stars. Castor and Pollux, the twins, are
easy to see, however. In the above
pictures, the star Beta Geminorum is also known as Pollux, while Alpha Geminorum
is known as Castor. These twins of
ancient mythology are easy to make out, as they are both magnitude 1 stars
(e.g. Castor about 1.6, Pollux about 1.1, both very bright). Their brightness is a combination of their
inherent large size and their relative nearness to Earth.
Castor is a triple star system (actually 6 stars, but only 3
are visible, with each of them being a spectroscopic binary). Two of the stars can be split in a small to moderate
size amateur telescope. The brightest of
the group is about magnitude 1.9, but the contribution of light from the other
stars in the group bring the overall magnitude to about 1.6. The largest components are bigger than our
sun, and the distance to the system is about 51 light years or about 16
parsecs.
Pollux has a slightly orange tint to it. It is probably variable (varies in
brightness). It is actually quite close
to the Earth, at about 34 light years, or about 10 parsecs. In fact, it is the closest giant star to the
Earth. It has at least one planet, a hot
Jupiter of about 2 to 3 Jupiter masses, that orbits at about 1.6 Astronomical
Units (about 150 million miles).
In the second picture, I used the Gimp sparkle filter to
punch up the view a bit. This filter
enhances bright spots in the picture, and can add spikes to really bright points. This is a bit reminiscent of what star maps
look like, with brighter stars shown as bigger.
You can easily see how Pollux and Castor outshine the other stars in
Gemini.
Here’s a close-up map of the same stars, from Sky and
Telescope, with the iPhone photo placed side by side.
Here’s the same image, but with the constellation lines for
Gemini drawn into the iPhone picture.
You can see how the iPhone did a pretty good job of capturing the main
stars of the constellation, though not all of them.
Some other highlights of Gemini:
- Gamma Geminorum is also bright, at magnitude
1.9, and is bout 109 light years away.
It’s about 3 times the size of our sun.
- Delta Geminorum is about magnitude 3.5, about 60
light years away.
- Epsilon Geminorum is a double star, about
magnitude 3.5 and is about 60 light years distant. It can be split in a moderate amateur
telescope.
- Epsilon is another double, about 900 light years
distant, that can be split in by binoculars or small scopes.
- Zeta is also a double star, which can be split
in binoculars or small scopes. It is
about 1200 light years distant, and is a Cepheid variable, a “standard candle”
used by astronomers to estimate distances to other stars
- Kappa is another binary, but hard to split
because the stars are not well separated.
- Eta is another double that can be split.
- The M35 open cluster is in Gemini. That’s a bunch of stars that are
gravitationally bound and close together, as seen from the Earth.
- The Eskimo nebula is a nice planetary nebula,
the last stages in a star’s evolution.
It somewhat resembles a person’s head, wearing a fringed parka.
- The Medusa nebula looks rather like its
namesake. It’s a planetary nebula, but
hard to see in an amateur telescope
- There are a number of other deep-sky objects,
mainly open clusters of the NC category.
- The Geminids meteor shower is a big show in
December.
- A recent finding is that a wandering red dwarf star
probably came near our solar system about 70,000 years ago. It would have been seen in the region of
Gemini, by ancient humans, but only if it flared, as red dwarfs tend to do. It may have perturbed some comets in the far
reaches of the solar system, though there were no major impacts known at that
time, so probably nothing hit the Earth.
·
In Greek mythology, Pollux was the son of Zeus. To get the full story, read the Wiki article.
“Leda and the Swan” is a famous poem by Yeats, related to
Pollux. Warning: Zeus was a pretty crazy
God.
In modern mythology, Pollux is notable for being the setting
of one of the original Star Trek episodes, “Who Mourns for Adonis”.
Sources:
Wiki
Google Images
Stargazing (Collins)
Space.com
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