Clouds could spoil Great Conjunction of Jupiter and Saturn

A rare moment in astronomy might well be lost to cloud cover in the Netherlands if the weather does not play along tonight. In an event that has not occurred in over 800 years, Jupiter and Saturn will only be 0.1 degrees apart from Earth's point of view and visible in the nighttime skies above the Netherlands.

Dubbed the "Great Conjunction", the celestial event gives the perception as if there is one large, bright star in the sky, which some have likened to the Christmas Star from the Nativity story in The Bible. The last time the Great Conjunction took place was in 1623, but it is the first time since 1226 the phenomenon will take place after sundown.

In principle, the conjunction should be at its most visible between 5:15 p.m. and 6:15 p.m., with sundown occurring just before 4:30 p.m. The planets will appear in the southwestern sky just above the horizon, and will be visible to the naked eye if there is an unexpected break in the dismal weather. A telescope or a good pair of binoculars can make Saturn's rings visible, as well as several moons circling both planets.

Dutch meteorological agency KNMI predicted the forecast for Monday afternoon to be rainy and cloudy. There will be another chance to see the planets' convergence on Tuesday at the same time. Thus far, the weather was also predicted to obstruct that viewing.

The two planets typically fall into alignment about every 20 years, but the distance separating them is usually much larger. The last time the convergence of Jupiter and Saturn was visible was in 1980, yet even then the distance between the two planets was ten times greater than it will be Monday night, similar to how they might appear in skies in the year 2040.

For those who can wait until 15 March 2080 there will be another possibility to see the Great Conjunction in very close proximity in all its glory, provided the Dutch weather allows it.