I have long thought that anyone who does not regularly - or ever - gaze up and see the wonder and glory of a dark night sky filled with countless stars loses a sense of their fundamental connectedness to the universe. ~ Bob Greene
When we look up at the night sky, we see an immense universe, populated
by more stars than there are grains of sand on our entire planet, and that's
just the observable universe. We know that each star is a Sun and around those
Suns are planets, and chances are, there's life on them. But for the majority of
human history, this was not the case. The dominant model in Europe, up to at
least the 17th century, saw the Earth as the center of the universe. The Sun,
the planets, and the stars, were thought to be placed in a series of crystalline
concentric spheres that rotated around it, beyond that lay Heaven. To suggest
otherwise, was at best a minority view, and at worst, heresy.
On any clear night, the night sky offers an ever-changing display of
fascinating objects to see, from stars and constellations to bright
planets, the moon, and sometimes special events like meteor showers.
Observing the night sky can be done with no special equipment, although a
map can be very useful, and a good
or binoculars will enhance some experiences and bring some otherwise invisible
objects into view.
The night sky is more than just the moon and stars, if you know when and where
For the star-gazers, you'll love
Interactive Planetarium, you set your location and it will tell you the name
and show you all the constellations and stars in your night sky. Absolutely
The night sky and studies of it have a historical place in both ancient and
modern cultures. In the past, for instance, farmers have used the state of the
night sky as a calendar to determine when to plant crops. Many cultures have
drawn constellations between stars in the sky, using them in association with
legends and mythology about their deities.
The anciently developed belief of astrology is generally based on the belief
that relationships between heavenly bodies influence or convey information about
events on Earth. The scientific study of the night sky and bodies observed
within it, meanwhile, takes place in the science of astronomy.
The visibility of celestial objects in the night sky is affected by light
pollution. The presence of the Moon in the night sky has historically hindered
astronomical observation by increasing the amount of ambient lighting. With the
advent of artificial light sources, however, light pollution has been a growing
problem for viewing the night sky. Special filters and modifications to light
fixtures can help to alleviate this problem, but for the best seeing both
professional and amateur optical astronomers seek viewing sites located far from
major urban areas.
Stars are, depending on how dark the sky is, hundreds or thousands of white
pinpoints of light in an otherwise black sky. To the naked eye, they all appear
to be equidistant on a dome above the earth because stars are much too far away
for stereopsis to offer any depth cues. Visible stars range in color from blue
(hot) to red (cold), but with such small points of faint light, most look white
because they stimulate the rod cells without triggering the cone cells. If it is
particularly dark and a particularly faint celestial object is of interest,
averted vision may be helpful.
The stars of the night sky cannot be counted unaided because they are so
numerous and there is no way to track which have been counted and which have
not. Further complicating the count, fainter stars may appear and disappear
depending on exactly where the observer is looking. The result is an impression
of an extraordinarily vast star field.
Because stargazing is best done from a dark place away from city lights, dark
adaptation is important to achieve and maintain. It takes several minutes for
eyes to adjust to the darkness necessary for seeing the most stars, and
surroundings on the ground are hard to discern. A red flashlight (torch) can be
used to illuminate star charts, telescope parts, and the like without undoing
the dark adaptation.
There are no markings in the night sky for Constellations, though there exist
many sky maps to aid stargazers in identifying constellations and other
celestial objects. Constellations are prominent because their stars tend to be
brighter than other nearby stars in the sky. Different cultures have created
different groupings of constellations based on differing interpretations of the
more-or-less random patterns of dots in the sky. Constellations were identified
without regard to distance to each star, but instead as if they were all dots on
Orion is among the most prominent and recognizable constellations. The Big
Dipper (which has a wide variety of other names) is helpful for navigation in
the northern hemisphere because it points to Polaris, the north star.
The pole stars are special because they are approximately in line with the
Earth's axis of rotation so they appear to stay in one place while the other
stars rotate around them through the course of a night (or a year).
Planets, named for the Greek word for "wanderer," process through the star field
a little each day. Planets, to the naked eye, look like additional points of
light in the sky. The disc is not apparent without binoculars or a telescope.
Venus is the most prominent planet, often called the "morning star" or "evening
star" because it is brighter than the stars and visible near sunrise or sunset
depending on its location in its orbit. Mercury, Mars, Jupiter and Saturn are
also visible to the naked eye.
Earth's Moon is a gray disc in the sky with cratering visible to the naked eye.
It spans, depending on its exact location, 29-33 arcminutes - which is about the
size of a thumbnail at arm's length, and is readily identified. Over 28 days,
the moon goes through a full cycle of lunar phases. People can generally
identify phases within a few days by looking at the moon. Unlike stars and
planets, the light reflected from the moon is bright enough to be seen during
Some of the most spectacular moons come during the full moon phase near sunset
or sunrise. The moon on the horizon benefits from the moon illusion which makes
it appear larger. The light reflected from the moon traveling through the
atmosphere also colors the moon orange and/or red.
Comets come to the night sky only rarely. Comets are illuminated by the sun, and
their tails extend away from the sun. A comet with visible tail is quite unusual
- a great comet appears about once a decade. They tend to be visible only
shortly before sunrise or after sunset because those are the times they are
close enough to the sun to show a tail.