Appendix D: Basic astronomy
In the early 17th century Italian Scientist Galileo, using a telescope smaller
than your Messier, turned it skyward instead of looking at the distant trees
and mountains. What he saw, and what he realized about what he saw,
has forever changed the way mankind thinks about the universe. Imagine
what it must have been like being the first human to see moons revolve
around the planet Jupiter or to see the changing phases of Venus!
Because of his observations, Galileo correctly realized Earth's movement
and position around the Sun, and in doing so, gave birth to modern
astronomy. Yet Galileo's telescope was so crude, he could not clearly
make out the rings of Saturn.
Galileo's discoveries laid the foundation for understanding the motion and
nature of the planets, stars, and galaxies. Building on his foundation,
Henrietta Leavitt determined how to measure the distance to stars, Edwin
Hubble gave us a glimpse into the possible origin of the universe, Albert
Einstein unraveled the crucial relationship of time and light, and 21st-
century astronomers are currently discovering planets around stars outside
our solar system. Almost daily, using sophisticated successors to Galileo's
telescope, such as the Hubble Space Telescope and the Chandra X-Ray
Telescope, more and more mysteries of the universe are being probed and
understood. We are living in the golden age of astronomy. Unlike other
sciences, astronomy welcomes contributions from amateurs. Much of the
knowledge we have on subjects such as comets, meteor showers, double
and variable stars, the Moon, and our solar system comes from
observations made by amateur astronomers. So as you look through your
Bresser Messier-Series telescope, keep in mind Galileo. To him, a
telescope was not merely a machine made of glass and metal, but
something far more—a window of incredible discovery. Each glimpse offers
a potential secret waiting to be revealed.
Objects in Space
Listed below are some of the many astronomical objects that can be seen
with your Messer series telescope:
The Moon
The Moon is, on average, a distance of 239,000 miles (380,000km) from
Earth and is best observed during its crescent or half phase when Sunlight
strikes the Moon’s surface at an angle. It casts shadows and adds a sense
of depth to the view (Fig. 50).
No shadows are seen during a full Moon, causing the overly bright Moon
to appear flat and rather uninteresting through the telescope. Be sure to
use a neutral Moon filter when observing the Moon. Not only does it pro-
tect your eyes from the bright glare of the Moon, but it also helps enhance
contrast, providing a more dramatic image.
Using your Messier-Series telescope, brilliant detail can be observed on
the Moon, including hundreds of lunar craters and maria, described below.
Craters are round meteor impact sites covering most of the Moon’s surfa-
ce. With no atmosphere on the Moon, no weather conditions exist, so the
only erosive force is meteor strikes. Under these conditions, lunar craters
can last for millions of years.
Maria (plural for mare) are smooth, dark areas scattered across the lunar
surface. These dark areas are large ancient impact basins that were filled
with lava from the interior of the Moon by the depth and force of a meteor
or comet impact.
APPENDIX D: BASIC ASTRONOMY
Looking at or near the Sun will cause instant and irreversible damage to your eye!
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