Starwerk Resources

Different parts of the sky are visible at different times of the year

This has to do with Earth's motion around the Sun. See our Article on What Stars Are Visible At Different Times Of Year to understand why. In addition, objects like planets, the Moon and comets have motions of their own. They wander against the background stars constantly. In fact, the word "planet" is based upon the Greek word for wanderer.

The stars themselves are much easier to keep track of. They are in the same place in the sky on a given day at a given time, and changes in their posiitons are only noticeble over immensely long times. You might even say that the stars move like clockwork.

The primary thing to keep in mind is that the seasons in the north and south are reversed: winter in one is summer in the other, and the same for spring and fall. Also, objects that are viewed toward the south from the Northern Hemisphere might be straight overhead, or even viewed toward the north, from a location the Southern Hemisphere. It just depends on the partiuclar celestial object and the location of the observer. These are just things to keep in mind.

The rest of this section gives a general outline of what you can expect to see at different times of year. Keep in mind that the sky visible from the Northern Hemisphere differs from that visible from the Southern Hemisphere, especially the parts of the sky closer to the poles. Our discussion will be mostly concerned with the Northern Hemisphere because that is where we (at Starwerk) are located. At the bottom of the page we link to a few other websites that keep track of things like the phase of the moon, the location of the planets and other changeable aspects of the sky.

• First, Find Some Dark Skies - The first thing you might want to do is find reasonably dark skies near to wherever you are. The Dark Sky Finder website provides useful informaton for choosing a nearby dark site. Of course, it might be that you are not particularly close to any dark sky area. This will be true if you are in a big city or most locations east of the Rocky Mountains (in the US). However, the dark sky website could still help you find a nearby lcation that is darker than your backyard. It has lots of other useful information about visual observations of the sky, too.

The Milky Way is visible in the Northern summer

• The Milky Way is visible in the evening from the end of May through late in the fall. This is the brighter part of the Galaxy, the part nearest its core. The Galaxy starts out low in the east in May. It moves progressively higher in the sky as the season progresses. By the first part of November the core of the Galaxy, which is seen far to the south from North America, near the constellations Scorpius and Sagittarius, has slipped below the southwest horizon. The more northern parts of the Galaxy gradually slide along the western horizon, moving northward as they set.

The times given above are for the brightest part of the Galaxy, toward its core. The other side of the Milky Way, the part opposite the core, is visible in the winter evenings running between the constellations Orion and Gemini and up past the bright star Capella. The parts of the Galaxy visible at this time of year much fainter than the parts of the Galaxy seen in the Northern summer. However, if you are in a region with dark skies you will still be able to see it.

We should also make clear that we are discussing when the Galaxy is visible in the evening. These hours tend to be more convenient for people. However, you can also view the Galaxy for several months earlier if you are willing (and able) to go out in the pre-dawn hours.

Since the Galaxy is easily visible at the times above, all the kinds of objects that are associated with it are also visible. These include open clusters, bright nebulae like HII regions, planetary nebulae, etc. All of these sorts of objects are associated with stars - often young stars, and those are mostly confinded to the galactic disk. An exception to this rule are globular star clusters. They are not part of the Glactic disk at all, they are part of the halo. However, since the halo is centered on the disk, there are many globular clusters visible when the summer Milky Way is visible, but they are visible at other times, too.

Of course, when the Milky Way is dominating the sky, it blocks our view of objects that are not inside it - and plenty that are, actually. That means that we do not see very many galaxies durning the northern summer and winter. Galaxies other than the Milky Way are best viewed in the spring and fall, in either hemisphere, when the Milky Way is not high in the sky.

So the upshot of all this is that if you attend one of our programs in the northern summer you are likely to see the brightest part of the Milky Way, as well as lots of star clusters and regions of active star formation. If you join us in the spring or the fall, you will likely see lots of galaxies, but the brightest parts of the Milky Way will not be easy to see. In fact, they might not be seen at all. So if you have an object or set of objects that you are keen to view and discuss, be sure you book a time when your objects will be visible.

Below we give a listing by season of which objects are easy to see.