This month, Mercury, Venus, Mars, Jupiter, and Saturn aligned in the southeastern predawn sky, providing a unique viewing opportunity for skywatchers. As they appear to move increasingly apart from one another in the early sky, the rare alignment of five naked-eye planets will begin to "break up"
The five planets appear to arc across the sky in a straight line, with Mercury near the horizon. This is the first time the five planets have been seen together above the horizon since December 2004.
While we've been able to see Saturn, Mars, Jupiter, and Venus in the morning sky for the past few months, Mercury was added to the unusual planetary alignment in June. On June 3, the little planet appeared alongside the quartet, only briefly peaking over the horizon before being obscured by the rising sun's glare.
Mercury, on the other hand, will become easier to spot in the morning sky around June 10. According to EarthSky.org, the planet will reach its greatest elongation, or farthest point from sunrise, on June 16, making it even brighter as the month proceeds.
Because they travel on the ecliptic, the plane of the solar system, the five worlds appear to line up. The planets are aligned in order of their distance from the sun, with Mercury being the nearest to the sun and appearing lowest on the horizon, and Saturn being the farthest away and appearing highest in the sky.
The planets appear close together to Earth watchers, although they are actually millions of miles or kilometers apart.
Unfortunately, this magnificent planetary alignment will not be visible for long. Saturn, Mars, Jupiter, and Venus, which we've been able to see in the early sky for the past three months, will become increasingly distant from one another starting in June.
The planets will spread out across the early sky over the following few months, "to the point where Venus and Saturn will cease to be morning objects for most observers by September."
M13, commonly known as the Hercules Cluster, is one of the best-known globular star clusters. Globular star clusters are spherical groupings of stars closely packed together in their centers, and M13 includes several hundred thousand stars.
Globular clusters are also quite old. The stars in M13 are considered to be roughly 12 billion years old, which is close to the age of the universe itself. Our own galaxy, the Milky Way, is known to have roughly 150 globular clusters. They orbit outside the galaxy's disk, tens of thousands of light-years above and below its spiral arms and most of its stars.
Find more skywatching highlights for the month of June here.
