You may have seen images being widely circulated on social media sites showing a planetary alignment above the Great Pyramid of Giza purported to happen this week. Some even label the alignment as a sign associated with Dec. 21, 2012, the end of the Mayan long count calendar and/or doomsday events. None of these are anything to worry about.
Like many hoaxes distributed via the Internet, these images are likely based on a nugget of truth which is being misinterpreted and the image altered to put the planets in more aesthetically pleasing yet impossible position. The arrangement of planets does
occur this week but in Antarctica, not Egypt. Other explanations for the image require an Earth-centered solar system, something the Copernican Revolution left behind back in the 16th century.
Accompanying claims that this close grouping of planets is a once in a multi-generation event are also false. As recently as last year, these planets appeared even closer together.
It is true that Mercury, Venus and Saturn line up nicely in the pre-dawn eastern sky this week. Early risers should take a moment to look. These planets were especially close to each other Monday morning, just 14 degrees apart. They were also distributed nearly evenly with Mercury near the horizon, bright Venus in the middle and dimmer Saturn above. A bit higher and to the South, the star Spica shines near the line of planets. Throughout the remainder of December, Saturn will continue to pull away from Mercury and Venus in the predawn sky.
Planetary alignment sounds like something rare, mysterious, or even scary, but it actually isn't a big deal. The word planet comes from the Greek word for "wanderer." Those planets, along with the Sun and Moon, wander at differing rates through the ecliptic, an imaginary line in the sky. Like athletes on a track running at different speeds, sometimes they meet up. This is nothing extraordinary and has been happening since the solar system was formed.
Keep in mind that while these planets may appear closer to each other, this is just from our perspective on Earth. The distance between these planets this week doesn't change as much as our eyes lead us to believe. On Monday, Venus and Saturn were about 851 million miles apart. As December moves on, they'll appear further apart in our morning sky each day but are actually drawing closer to each other by about 1 million miles daily.
Tony Rice is a volunteer in the NASA/JPL Solar System Ambassador program and software engineer at Cisco Systems. You can follow him on twitter @rtphokie.