Watch nine worlds in one night by stepping out after sunset: most of the planets are now easily visible, inching across the sky like bumper-to-bumper traffic. The procession began last Wednesday, when the crescent Moon slid alongside ringed Saturn, the spectacular star cluster Beehive flanking them. Come June 15, butterscotch Mars, now sitting alongside Saturn, makes a dramatic pass in front of the Beehive. On June 17, Mars and Saturn close in on each other as if they’ll collide: hold your thumb at arm’s length and the two planets easily fit behind its tip!
The brightness of the Sun makes it difficult to spot planets, so we see them only when they are far out. Mercury was farthest from the Sun on June 2, as will be Venus — now shining at a dazzling magnitude of -4.2 (almost 15 times brighter than Sirius, the brightest star) — on June 8. Afterwards, they will swing closer to the Sun before disappearing in its harsh light. Meanwhile, Jupiter rises opposite the setting Sun, as though the two occupy opposite ends of the horizon. At this ‘opposition’ tomorrow (June 5), Jupiter will be one of the most luminous objects in the sky. Using a telescope, you could also see Uranus, Neptune and Pluto. For the ninth world, glance down at the ground.
The chances of seeing all nine planets in a single line of vision are so rare that the solar system won’t last long enough. To an observer, its eastward movement in its orbit around the Sun ‘shifts’ the planets westwards among the stars. This, combined with the planets’ real eastward movement along elliptical (egg-shaped) orbits, produces the loped paths we see as they ‘rise’ and ‘set’ in the sky.
These alignments tell us how the solar system formed more than four billion years ago, condensing out of a nebular dust cloud that flattened into a huge disc. The pathway of planets is what remains of that dust cloud. Instruments like the Hubble Space Telescope show us the creation of new solar systems: some of the large lumps of material in those distant dust discs that are actually planets in formation.