Planetary parade: Mercury falls into line for rare seven-planet alignment

The seven will appear to form a straight line in the night sky in display that won’t be seen again until 2040. Seven planets will appear to align in the night sky on the last day of February in what is known as a planetary parade. These planetary hangouts happen when several planets appear to line up in the night sky at once.

“A planetary parade is a moment when multiple planets are visible in the sky at the same time,” said Dr Greg Brown, an astronomer at the Royal Observatory Greenwich, told PA Media. “How impressive a parade it is will depend on how many planets are in it and how visible they are.”.

This week, all seven planets are technically visible in the sky at once, though they are not all equally easy to spot. “Mercury, Neptune and Saturn are all very close to the horizon in the early evening and, particularly in the case of Neptune and Saturn, will struggle to be seen in the twilight,” Brown said. “In addition, Uranus, like Neptune, is very faint, making it almost impossible to find without a pair of binoculars or a telescope.

“Venus, Jupiter and Mars, however, are all very easy to see with the unaided eye.”. A parade of four or five planets visible to the naked eye happens every few years, according to Nasa. “Groups of three, four or even five planets being visible aren’t uncommon, regularly appearing throughout each year,” Brown said. “But the more planets are involved, the more things need to be aligned to be visible at once. This makes full seven-planet parades fairly rare.”.

A similar parade took place last June, but only two planets could be seen without any special equipment. Six planets were visible in January – four to the naked eye – and now a dim Mercury joins the gang. This month, Venus, Mars and Jupiter are visible to the naked eye. A faint Saturn and Mercury are close to the horizon, making them hard to spot. Uranus and Neptune can be glimpsed with binoculars and telescopes.

“Planetary alignments occur because the planets in our solar system orbit the Sun within roughly the same plane, known as the ecliptic plane,” Dr Shyam Balaji, a researcher in astroparticle physics and cosmology at King’s College London, said. “As they orbit at different speeds and distances from the Sun, there are moments when they appear to line up from Earth’s perspective.”.

Balaji said the best time to see the alignment in the UK was 28 February, “shortly after sunset, when the planets will be positioned above the western horizon”. The same is true in Australia, where stargazers should look north after sunset, and the US, with experts suggesting those hoping to see the celestial show should head out about 30 minutes after sunset and stay away from bright lights.

Stargazing apps can help people find out where to look just after sunset around the world. To find the planets with a telescope, look for moon shapes, Brown said. “Using a telescope, try looking for the moons of Jupiter or the shape of the illuminated part of Venus’s surface – like a tiny crescent moon.”.