27Jun2014

7 Great Things You Can See Without A Telescope

Viewing

 Backyard Astronomy Basics

Binoculars are usually labeled with two numbers, such as 7×35 or 10×50. The first number tells you ‘magnification’ – how much your binoculars will magnify things in your field of view.

A magnification of 7x to 10x is usually enough for basic astronomy. At higher magnifications, the image tends to appear shaky (unless you have a higher-end set of binoculars with image stabilization).

The second number is more important; it describes the diameter (in millimeters) of the primary lens, or aperture, of your binoculars. A wider aperture will gather more light, which will enable you to see fainter objects in the sky. On the other hand, wider apertures mean wider, heavier binoculars, which can be unwieldy and impractical. In general, 40- to 50-mm is enough for basic astronomy, while apertures in the 70- to 100-mm range will be too large and heavy to use without a tripod.

Satellites and Space Stations

On clear nights you can watch satellites pass overhead. The biggest and brightest are visible even with the naked eye, but a good pair of binoculars will let you see even more satellites in the night sky. If you know where to look, you can track the passing of everything from commercial telecommunications satellites to the International Space Station (ISS).

Even with binoculars, some satellites appear simply as bright points of light moving quickly across the sky. The light that you see is sunlight reflecting off the satellite’s surface. Because you need reflected sunlight to see a satellite, the best time to look for them is generally about an hour after sunset or an hour before sunrise. During the middle of the night, most satellites are fully in Earth’s shadow.

To find out which satellites pass over your location and when to see them, visit heavens-above.com, select your location, and check predictions for several listed satellites. The table will tell you when the satellite will pass overhead and where in the sky to look.

The ISS is one of the easiest to spot. It is brighter than almost anything in the sky besides the moon, and it moves across the sky faster than most airplanes.

The Moon

With the power of binoculars you should be able to spot details of the lunar surface such as the dark plains of cooled lava known as maria; the pale, crater-scarred lunar highlands; and many large craters. To find one of the largest and most impressive lunar craters, imagine the moon as a clock face and look at the 6 o’clock position, where you should see a large crater with white rays extending out from its edges. This crater is called Tycho, and the meteor that formed it slammed into the moon about 25 million years ago. The white rays are rock and dust thrown upward by the impact.

For the best view of lunar craters, look along the daylight side of the terminator—the line between the dark side of the moon and the sunlit side. Along this boundary, objects cast longer shadows, which makes the moon’s topography stand out more clearly. Because the terminator moves across the lunar surface as the moon’s phases shift, you should be able to see a different section of the every few nights.

During the waxing crescent phase, when the moon looks like just a crescent-shaped sliver in the western sky, your binoculars can reveal the rest of the lunar disc, faintly lit by sunlight reflected from Earth.

Planets

Mercury and Venus usually appear low in the sky at twilight. Like our moon, these two inner planets appear to have waxing and waning phases, which makes them easier to spot with binoculars (a half-circle or cresent shape is clearly a planet rather than a star). Venus is much brighter than Mercury. In fact, you may get the best view of Venus at twilight rather than after dark because the planet reflects so much light that it can create a bright glare.

Mars is easy to spot, thanks to its distinctive red color. To get a sense of how much closer to Earth it is than the distant stars, find a bright star in the night sky and watch as Mars passes in front of the star and eclipses it.

You can also use your binoculars to see alien worlds that might hold liquid water or even life. Use your star chart or sky calendar to find Jupiter, and look for the four smaller points of light nearby. These are Jupiter’s four largest moons: Io, Ganymede, Callisto, and Europa, which were first discovered by the astronomer Galileo Galilei in 1610. Scientists know that Ganymede and Europa have liquid water beneath their icy crusts.

You can recognize Saturn by its yellowish color. Through binoculars you can sometimes see its moon Titan, whose surface contains seas of liquid methane. Methane is also abundant in the atmosphere of Saturn’s more distant neighbor, Uranus, which has a slightly greenish color. Neptune, the most distant planet in the solar system, is hard to distinguish from stars, but with the help of a good star chart, you can get a slightly closer look through your binoculars.

To find out when planets are visible in the night sky and how to find them, check a sky calendar. You can access free sky calendars from earthsky.org, skymaps.com, or stardate.org.

Comets and Asteroids

Most telescopes are too narrow to view a whole comet at once, but binoculars offer a wide field of view to take in the whole spectacular sight. Comets tend to be distinctive objects in the night sky. They look like fuzzy blobs of light, often with glowing tails, and they change position in the sky from night to night.

This year, Comet Pan-STARRS will be visible through the end of June and again in September’s early morning sky. In late August you will be able to see Comet Oukaimeden just east of the constellation Orion. In early October you can watch Comet Sliding Spring approaching Mars. It will eventually brush against the red planet on Oct. 19, so close that the comet’s “comma” of gas and dust may actually cause meteor showers on Mars.

About a dozen known asteroids are also visible with binoculars. They are hard to distinguish from stars, but if you watch the sky closely, you may notice objects that move around from night to night.

Stars and Star Clusters

On a clear night, away from urban light pollution, you can usually see about 3,000 stars with the naked eye. With a modest pair of binoculars, you can see about 100,000. In the city those numbers are lower, though binoculars can help cut through the light pollution.

The stars Mizar and Alcor form one of the easiest clusters to find. In the Big Dipper, Mizar is the star at the bend of the Dipper’s handle. If you look closely on a dark night, you should be able to see Mizar’s nearby partner, Alcor, with the naked eye. Some sources claim that in ancient times, the Roman Army used Alcor as a vision test for prospective archers. Through binoculars you can see the pair even more clearly, and you may be able to spot a third star called Mizar B.

In winter and spring the Beehive Cluster can be seen northeast of the constellation Orion. This star cluster, about 500 light-years away, is where scientists found the first exoplanets orbiting stars like our sun. It may appear a little cloudy to the naked eye, but with binoculars you can see hundreds of stars in this cluster, from massive, bright blue stars to orange giants and red dwarfs.

You can also look for the Double Cluster in the constellation Perseus during the autumn months, the Pleiades to the right of Orion’s Belt, and others with the help of a good star chart

Nebulas

Star clusters are born in clouds of gas called nebulas. You can use your binoculars to explore several of these star factories, including the Orion Nebula. Find the constellation Orion and look for the slightly fuzzy star in the middle of Orion’s sword. This “star” is actually the Orion Nebula, a cluster of new stars forming about 1,500 light-years from Earth, in our own neighborhood of the Milky Way Galaxy. The silvery shape you see is a mass of hydrogen and helium about 20 light-years wide, lit by the fires of brand-new stars.

Galaxies

Although binoculars will not reveal much detail about the shape and structure of galaxies, you can see the outlines of them with a good pair of binoculars and a little persistence. Choose a moonless night, and roam far from light pollution.

The Andromeda Galaxy, about 24 million light-years from Earth, appears as a small, pale, cloudy oval in the sky during the autumn and winter months. If you find the W-shaped constellation Cassiopeia, the right-hand leg of the “W” will point toward the Andromeda Galaxy. You may want to refer to your star chart to locate the galaxy more precisely.

Two spiral galaxies, M81 and M82, are visible during most of the year. Look in the constellation Ursa Major, near the bowl of the Big Dipper. With your binoculars’ wide field of view, you should be able to see both galaxies together, although they will appear as a pair of bright blurs in the sky rather than detailed spirals. M81 is the brighter of the two. These two galaxies are slowly moving even closer together in space.

The relatively dim Pinwheel Galaxy is more challenging to spot even with a good telescope, but it is technically visible with binoculars under the right circumstances. Look just above the handle of the Big Dipper, near the double stars Mizar and Alcor. Your star chart can help you pinpoint the galaxy more precisely. Source: Popular Mechanics

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