There are many things that can make lights in the nights. As astronomers we see many of them nightly: stars, planets, moons, asteroids, comets, meteors, deep space objects, and galaxies. A close eye will even catch some of the man-made objects: satellites, high-flying aircraft and balloons. This article will address not objects so much as phenomena. They are often difficult to see, requiring very dark and clear skies. And some of them require you to be in the right place at the right time. My challenge to you See them all!

Aurora - Also known as the Northern lights (keep in mind that there are also Southern Lights) occur at higher latitudes. On rare occasions they can be seen as far South as Houston, but the further North you are the better. Auroras are caused by disturbances on the suns surface that appear to us as sunspots and their associated solar flares. Charged particles are expelled from the Sun at speeds over 500 miles per second. When these particles reach the Earth, after a couple days in space, they hit the Earths magnetic field. They then travel along that field to the night side of the Earth. The more energetic particles pass from these magnetic field lines into the atmosphere. As they drop, they interact with molecules in the Earths atmosphere causing them to give off light. What we see are curtains of light in the sky. They are mostly green, but lower-energy particles may cause a red glow near the lower end of the aurora.

Zodiacal Light - If you are in a site with dark skies, you may be treated to a show of the Zodiacal Light. The name is from its location, and has nothing to do with astrology. Immediately after sunset, or before dawn, triangles of light are sometimes seen moving from the horizon to a point in the sky above where the sun set or will rise. It is actually a band of light that follows the path of the ecliptic (the path that the planets appear to follow as they travel through our sky). Dust from the solar system forms a flattened disk around the sun in the inner solar system. Particles that are to large to be blown away by solar radiation are slowly spiraling into the Sun. They are in the same plane as the planets (hence along the ecliptic). These particles from 0.1 to 100 micrometers reflect sunlight back to observers on Earth. The best time to see this is in September and October at middlelatitudes. Begin looking before the start of morning astronomical twilight (90 minutes before sunrise). It may reach the brightness of the Milky Way. The light may be as wide as about 15 degrees at the horizon and the triangle may extend up to 40 degrees altitude..

Noctilucent Clouds - We have all seen the great (not for astronomy) displays that clouds make at sunset. The effect is most pronounced in the West (or East for sunrise). At Northern latitudes (above 50 degrees)(and probably far Southern latitudes as well), very high clouds produce a similar effect during the summer months. The clouds are up to 9 times higher than normal clouds and are made up of ice-covered particles of vaporized meteors. They are usually smaller than 90 nanometers and give off light in bright silver, blue, and orange. They begin to show up after sunset at about 30 degrees altitude. As the sun sinks further below the horizon, the visible clouds drop in altitude. This is quite rare. It may not happen for months at a time.

Gegenshein - This is another middle-latitude phenomenon. It is actually thought to be very closely related to the Zodiacal Light. At a point in the sky, directly opposite of the sun, there is a very, very faintly glowing spot. It is believed that the same dust particles that cause the Zodiacal Light are reflecting sunlight back at the Earth. This spot is even fainter than the Zodiacal Light, and any street lights or moon will make it impossible to see.