Mercury, Venus, Mars, Jupiter and Saturn are aligning in this order for the first time since December 2004. It will be easiest for observers to see the event on Friday, June 24.
Five so-called "naked-eye" planets were visible from June 3 and 4. The quintet could be seen with binoculars for about 30 minutes until Mercury was obscured by the Sun's glare.
However, it would be best to watch on June 24. According to Sky & Telescope's Observing Editor Diana Hanniken, all five planets are becoming easier to see, even though the distance between Mercury and Saturn is increasing.
According to Hannikainen, the fading crescent will also join the journey between Venus and Mars, thus the morning sky on the 24th "will present a spectacular spectacle."
The planets should be visible in the days before this. According to Sky & Telescope, the line-up is best viewed on June 24, 45 minutes before sunrise. On the eastern horizon, it should be clear.
According to NASA, the four planets visible to the naked eye have been aligned for the past several months.
However, Saturn, Mars, Jupiter and Venus will spread out in the coming months. Most observers will not be able to see Venus or Saturn after September.
The M13 globular star cluster, a closely packed globular collection of stars, will be another celestial event to be observed in June.
According to NASA, many of the stars in M13, often referred to as the Hercules cluster, are thought to be about 12 billion years old, or nearly as old as the universe.