Space phenomena viewable by the human eye

Published March 21, 2012

| NewsCore

You don’t need a telescope to appreciate the night sky. People have gazed at the cosmos with nothing but the naked eye for thousands of years. Here are five space phenomena one can see with the naked eye.

The changing position of the setting sun 
Over time, it’s possible to see the sun’s rising and setting position. On March 20, the spring equinox occurs, and the sun sets due west in the sky, according to Christopher G. De Pree, professor of astronomy at Agnes Scott College and co-author of “The Complete Idiot’s Guide to Astronomy.” 

At that time, if you pick an observation spot and a landmark, “you will be able to see that the position of the sun at sunset moves significantly over time, until June 20 when the summer solstice arrives,” he said. On that day, the sun will set far north, and then it will slowly start setting due west again until September 22. If you make a note of the setting sun’s position once a week, you will see the difference.

The phases of the moon
The moon’s appearance changes as it goes through its lunar phases. The half of the moon facing the sun is always lit by the sun, but our view of the moon from Earth is always changing. We can watch what appears to be a full moon, a completely dark moon (new moon) or one of the shades in between. The position and phase of the moon will change noticeably each night. A full lunar cycle takes over two weeks.

A lunar eclipse
When the moon passes into the Earth’s shadow, this creates a lunar eclipse. “During a lunar eclipse, the disk of the moon gradually falls into darkness, until the entire disk of the moon is in the shadow of the Earth, and it can then be seen as glowing red in the light refracted through the atmosphere of the Earth,” De Pree said.

A solar eclipse
Solar eclipses are less common than lunar eclipses. This occurs when the Earth passes into the shadow of the moon. The relative rarity of this eclipse is due to the Earth’s bigger  size. Each solar eclipse is visible from a certain location on Earth.

The Andromeda Galaxy
Named after the princess from classical mythology, Andromeda is the most distant object visible to the naked eye. It is also referred to as Messier 31. De Pree explained, “It is similar in size to our Galaxy (the Milky Way), and is about 2.5 million light years distant. Everything else visible (without a telescope) in the night sky is in our own Galaxy.” With the naked eye, it appears a fuzzy, faint star. With binoculars, you can make out the elliptical shape of the galaxy. Scientists estimate that we will collide with Andromeda in a few billion years.