Although there are thousands of astronomical objects worth observing in the night sky, all astronomers, both amateur and professional alike, will tell you that they have their own personal favorites. These might include lingering early memories, such as the first sighting of the Milky Way’s largest globular cluster, Omega Centauri, or the first splitting of a difficult binary star system, such as observing the double star Albireo in Cygnus, whose brighter yellow star presents a striking contrast to its fainter blue companion. Whatever the case may be, the following list looks at ten celestial objects most astronomers agree are worth a second look.
It is possible to spend a life time observing the moon, and still discover something new every time you observe it. The play of light and shadow, the amount of illumination, and the libration of the moon can sometimes obscure some features, but bring them sharply into focus at other times. A good time to observe the moon is during daytime when it is visible, and quite often, you will discern detail that is not visible at night.
The moon is an excellent training ground for new observers, since many features become visible only during some illuminations, but mostly because the use of the correct magnifications is required to see some features. High magnification are not always the best option, so use the moon to practice using different magnifications under different conditions before you venture further into the solar system, and beyond. One thing is certain, though, you will keep coming back to moon!
Finding Mars is one of the most rewarding experiences any novice star gazer can have, and while it first may look nothing more than a small reddish disc, with a bit of practice even a small 4″ telescope can reveal tantalizing detail, such as the Red planet’s darker regions, and the formation, and subsequent disappearance, of its polar ice caps as the seasons change there. If you don’t have a go-to scope, Mars offers an excellent opportunity to learn your way around the night sky, since during certain times of the year it is easy to confuse the Mars with Antares located in the constellation Scorpius, which is a giant red star.
Venus also displays phases, just like the Moon, and although it may sometimes be difficult to obtain a fine focus on Venus, with good optics, and some practice with the fine focus control, it is possible to view the phases of the planet as its illumination from the Sun changes. Venus may not offer any detail other than it’s phase, but you will want to see it again and again.
The King of the planets always offers a rewarding viewing experience, since the detail on its colorful bands is forever changing. However, fine detail is only visible in larger amateur instruments, but even modest equipment, such as the photo taken by the 130mm (5″) telescope opposite, will reveal the equatorial bands and the four Galilean Moons as they weave their way around the gas giant. Of particular interest is the Great Red Spot on Jupiter, which is visible during good seeing conditions with even modest equipment. Once you start tracking the movement of the Spot, you will want to return to Jupiter for as long as it is visible. Since its discovery, the Great Red Spot has moved more than a 1,000 degrees, and at one point, it was even out of sight on the far side of the planet. See how well you can track this storm (that is larger than the earth) on the “surface” of Jupiter.
When Saturn’s rings are tilted with respect to our line of sight, the planet offers the most spectacular sight in the entire solar system. Even modest equipment, such as a 4″ telescope will reveal the splendor of the ring system, but be aware that you may be disappointed at your first sighting of the planet. The ring system changes its inclination to our line of sight, and at certain times the rings disappear altogether when they are face-on to earth. The rings are only a few tens of kilometers thick, so wait for a few months, and look at Saturn again- you will be glad you did! The “gap” in the rings to the right of the planet is caused by the shadow of the planet as it falls across the ring system.
Pleiades Star Cluster (M45)
Also known as the “Seven Sisters”, this small cluster in the constellation of Taurus consists of several dozen stars, of which only a few are visible without optical aid. However, even a small telescope (2.4″ to 4.5″) will reveal most of the stars in the cluster, which incidentally, are hot blue stars of roughly the same age, and composition. It is best to view this cluster from a dark site, and at a low magnification. Higher magnifications reduce the field of view, which means that most of the cluster is lost to view. Lower magnifications and dark skies also make it easier to see the bluish haze, which is the dust and gas in a large cloud that is moving across the cluster.
The Andromeda Galaxy (M31)
At 2.5 million light-years from Earth, Andromeda may be our closest neighbor in the Local Group of Galaxies, but it will present you with your first real test in finding dim objects. As with other colorful objects, photos of Andromeda are the result of exposures through different filters, but in your telescope, it will appear as a large, fuzzy patch without any real detail. However, the real reward will be in having found it in the first place. The key to finding this large spiral galaxy is finding the constellation of Pegasus first, and then from there you can find it located in the adjoined constellation of Andromeda using a good star chart or atlas. Once you have it in your sight, though, you can appreciate the fact that you are watching a huge galaxy that is approaching you at a speed of 125 kilometers per second.
The Orion Nebula (M42)
Because Orion lies almost on the celestial equator, it is visible from both hemispheres, and is one of the most recognizable shapes in the entire sky. The “waist” of the Hunter consists of three stars, and hanging from the Belt of Orion, as it is also known, are a further three stars that form Orion’s Sword. The “star” closest to the waist is in fact a small cluster of stars, but the second one down is a large nebula known as the Orion nebula that with a small scope and steady gazing will reveal a beautiful bluish tinge.
The Ring Nebula (M57)
The Ring Nebula in Lyra may be as difficult to find as Andromeda, but it will reward you in an unexpected way. It is one of only few objects that shows anything close to its true color in a telescope, and you will want to look at it for as long as you can. It is located between two rather bright stars, Sheliak and Sulafata, in the constellation Lyra, and you need to increase the magnification of your eye pieces as you close in on it. Higher magnifications tends to “darken” the background, so when you get it right, the Ring will leap out at you. Enjoy the sight; the search will have been well worth the effort!
The Crab Nebula (M1)
Also known as M1, being the first item in the Messier catalog, this nebula got its name from Lord Rosse, who sketched it after viewing through his 72-inch telescope, which happened to be largest telescope of its kind in the world in 1845. In the original sketch, the nebula looked like a crab, hence the name Crab Nebula. In reality, the nebula is the remains of a star that exploded as a supernova in 1054. Chinese astronomical records identify it as the “guest star”, and also mentions the fact that it was visible during the day. Today however, it can only be seen at night on the southern horn of Taurus, which is a constellation to the southeast of Orion. For the best viewing, use a magnification of around 200 times.
There are many more…
The few objects on this list represents a minuscule fraction of what is visible with an amateur instrument, but all of the above items have their own particular challenges. However, challenges are only stepping stones, and as you learn the sky and develop your observing skills, you will eventually start to “discover” other treasures on your own. Enjoy the journey!