Even in the night sky of the city, you can observe the solar system and bright stars. Here is a quick overview of what you can learn to find in the sky.
Because of the glow of city lights, you can only see tens of stars in the night sky. The longer you are in the dark, the more your eyes will adjust to it, and the more stars you will see. Try counting the number of stars you can see on any given night. Here is a list of the 15 brightest stars (ranked according to brightness) visible from North America, along with their magnitudes (see Science Stuff), lower numbers are brighter:
- Sirius, -1.5
- Arcturus, 0.0
- Vega, 0.0
- Capella, 0.1
- Rigel, 0.1
- Procyon, 0.3
- Altair, 0.6
- Betelgeuse, 0.7 (average: 0.2 to 1.2, variable)
- Aldebaran, 0.9
- Spica, 1.0
- Antares, 1.1
- Pollux, 1.2
- Fomalhaut, 1.2
- Deneb, 1.3
- Regulus, 1.4
Orion and the Big Dipper are probably the most recognizable constellations in the sky. Although the Big Dipper doesn’t have any stars on this list, Orion has two: RIGEL and BETELGEUSE. On the magnitude scale, I’ve found that on good, clear nights, I can spot stars as faint as about magnitude 3.5 in the Chicago urban sky.
These 15 stars appear in the night sky (in North America) at different times over the course of the year. Below is a list of the seasons and which of the above stars is best visible in the evening sky (before midnight). There is some overlap, of course, and there isn’t a strict cutoff between the seasons, but this gives you a rough idea of when to look for these. Find all 15 over the course of the year!
- Winter (December/January/February): Sirius, Capella, Rigel, Procyon, Betelgeuse, Aldebaran, Pollux
- Spring (March/April/May): Arcturus, Capella, Procyon, Spica, Pollux, Regulus
- Summer (June/July/August): Arcturus, Vega, Altair, Antares, Deneb
- Fall (September/October/November): Vega, Capella, Altair, Fomalhaut, Deneb
You’ll notice that there are more bright stars in the winter skies. Fortunately for us, winter skies feature longer nights, so you have more time to see these stars. VEGA, ALTAIR, and DENEB are the three points in the so-called Summer Triangle. Since there are only 5 of the top 15 stars visible in summer, you can see why these three dominate the summer sky.
Planets vs. Stars
The planets vary in their brightness (depending on their distance to Earth, for example), but VENUS and JUPITER are brighter than all of the stars in the night sky. The other planets are generally similar to the top 15 stars in brightness. When looking at the night sky, the easiest way to tell planets from stars is that planets don’t twinkle while stars do. This is because planets are close enough to us that they appear as tiny discs; stars appear as small points whose light can be affected by turbulence in the Earth’s atmosphere.
Both planets and stars have characteristic colors. For example, MARS is orange-red, as are the stars BETELGEUSE and ANTARES. I’ll point out the colors of other stars and planets in the main blog.