This Friday, 28th February, a rare astronomical event will take place as all the planets of the Solar System become visible from the Canary Islands after sunset. While this alignment is largely a matter of perspective rather than a significant cosmic event, it provides a unique opportunity for sky-gazers to observe and appreciate the structure of the Universe, as it won’t happen again until May 2161.
Astrophysicist Alfred Rosenberg, from the Instituto de Astrofísica de Canarias (IAC), has described the phenomenon in an article titled “Great Planetary Alignment of 28th February: The Planets Parade This Carnival”, coinciding with the start of the carnival festivities.
For a full week, all planets will be visible simultaneously after sunset. However, Saturn will soon disappear from view due to the Sun’s increasing brightness, followed by Venus and Mercury by mid-March.
The alignment occurs because all planets orbit the Sun in roughly the same plane, causing them to appear distributed along an imaginary line in the sky known as the ecliptic. Contrary to popular belief, planetary alignments do not mean the planets are positioned in a perfect straight line relative to the Sun. Instead, as long as several planets are on the same side of the Sun, they appear aligned from Earth’s perspective.
During this event, seven planets will be visible, with five visible to the naked eye - Mercury, Venus, Mars, Jupiter, and Saturn, while Uranus and Neptune will require a telescope.
The Moon will also join this grand celestial parade from tomorrow onwards. Venus will be the easiest to spot, being the brightest object at medium height in the western sky. Jupiter, another bright planet, will be nearly overhead at sunset, while Mars, with its distinct reddish hue, will be visible further east. Mercury will be positioned near the western horizon, and Saturn, though fainter, will be found between Mercury and the horizon.
Although planets will appear as mere bright spots to the naked eye, telescopes will reveal more details. Venus, the brightest, will appear large due to its proximity to Earth, though its thick atmosphere obscures surface features. Jupiter’s brown and ochre cloud bands and its four Galilean moons will be clearly visible.
Saturn, while impressive, will be difficult to observe due to its closeness to the Sun and dense atmospheric layers. Mars, though much smaller than Jupiter, will still display some surface details, but the outer planets remain too distant for significant features to be distinguished.
For the best view, Rosenberg advises heading out around sunset at approximately 7:05pm and waiting for the optimal moment at 7:45pm. By 7:50pm, Saturn will no longer be visible. Observers should look for a location free from light pollution, with a clear view of the western horizon, ideally at a higher altitude to avoid clouds.
Planets have been identified since ancient times due to their movement against the background of fixed stars. However, given the long orbital periods of the outer planets, it is unusual for all planets to be positioned on the same side of the Sun at the same time.
The next full planetary alignment is set for 19th May 2161. However, a more accessible event will occur on 8th September 2040, when all planets visible to the naked eye, along with the Moon, will be clustered in a relatively small area of the sky.
This year also offers other celestial alignments. On 25th April, Saturn, Venus, Mercury, and the Moon will be visible together at dawn, while on 20th August, Jupiter, Venus, Mercury, and the Moon will align in the night sky.
