Mars, Saturn, Regulus put on evening show in July skies

William Atkins
Sunday, 29 June 2008 22:15

Science - Space

Just remember, too, that when your eyes see the light from Regulus, and the reflected light (it originates in the Sun) from Mars, Saturn, and the Moon, you are seeing light that has traveled much different distances and times.

Light only takes a little over one second to reach the Earth after it bounces off the Moon. Photons of light travel at about 186,000 miles (300,000 kilometers) per second. The Moon is about 238,900 miles (384,400 kilometers) from Earth.

Light reflected off Mars, on the other hand, takes about 17 minutes to reach the Earth, and light reflected off of Saturn takes about one hour to reach our home planet.

The star Regulus produces its own light, and the light from this star takes about 77 years to reach us because the star is about 77 light-years away from us (where light travels a distance of one light-year in one Earth-year).

While watching these planets, remember that because Mars and Saturn are so low in the sky, the two planets could look a bit fuzzy due to the large amount of atmosphere that their light must travel through to get to our eyes.

And, not to forget the eastern part of the night sky: On the other side of the evening sky, just after sunset, skygazers will find the largest planet in our solar system, Jupiter. It will appear as a very bright point in the sky (about a magnitude of -2.7, over six times as bright as Saturn), being at its closest point to Earth—at about 400 million miles (645 million kilometers) away.

At this time, Jupiter is in opposition—meaning that it is opposite of the Sun. When the Sun arises in the eastern morning sky, Jupiter is going down in the western sky, and when the Sun sets in the western night sky, Jupiter is coming up in the eastern sky.

During the month of July, people gazing with their telescopes should be able to see its Galilean satellites, the distinct bands of color around the giant gaseous planet, and its Great Red Spot.