Running in the shadows: Solar eclipses outside Earth

Running in the shadows: Solar eclipses outside Earth
Partial Solar Eclipse

When we talk about solar eclipses, one often imagines the moon blocking the sun in a dazzling show of lights. However, many fail to realize until pointed out that solar eclipses happen on other planets too! More in this blog.

Look, an Eclipse!

Solar eclipses happen when a moon of a planet partially or completely blocks the Sun. Eclipses are far more common than you would have imagined. On our planet, they happen 4 times a year on average. Our moon’s orbit is tilted by around 5 degrees relative to the earth’s solar orbit, hence the low number. Had the Moon’s orbit been on the same plane as the orbit of Earth around the Sun, there would have been solar eclipses every new moon.

Wrath of god

Solar eclipses have been considered an omen probably since the beginning of mankind. The paranoia is justified considering the lack of knowledge in early humans. The sun is the single source of power for everything on Earth. Without the sun our planet’s surface would dangle near -270 degrees Celsius and life will obviously not exist. The sun’s status as the absolute god was beyond any doubt. Yet there was an unknown thing which, once in a while, was able to hide the sun for many minutes. Something that overshadowed god? Must be a demon! Even with the scientific advancements today, in many countries like India, superstition always finds its way.

Inner Solar System

Mercury and Venus do not have moons, and hence cannot have Solar Eclipses. While we have witnessed Earth’s eclipses, Mars has eclipses too!

Earth

If you don’t feel special about living here yet, here’s a fact – you cannot witness the magical eclipses seen on Earth anywhere else in the solar system. The moon is roughly the same size as the sun. This allows us to see annular (ring) eclipses when the moon is slightly smaller, or a total solar eclipse if the moon is larger. Fortunately, the moon is not too large for us to enjoy viewing the Sun’s corona

Mars

Eclipse of Phobos (left) and Deimos as captured by the Curiosity rover.

Mars could have witnessed the same type of eclipses that Earth does, but alas its moons, Phobos and Deimos, are way too small to cover the entire disk of the Sun. Phobos being the largest (though just 22 km in diameter) and the closer moon casts the largest shadow. Deimos on the other hand is a mere 12 km wide, and is way far away than Phobos, hence appearing as a large dot traversing the sun.

Gas Giants

The gas giants Jupiter and Saturn enjoy multiple eclipses at the same time because of their large number of moons. Although there’s a catch – their moons occult the Sun completely, because of the large distance that makes the Sun appear like a small, bright dot from their point of view. You won’t be able to witness them as these planets don’t have a surface, however we have witnessed how eclipses on Jupiter, Saturn and Uranus appear when seen from space, thanks to the Hubble Space Telescope and numerous space probes sent to these planets.

Jupiter

Io, Jupiter’s third largest moon, casting a shadow on the planet.

Jupiter is popular among the extraterrestrial solar eclipses. The planet’s four largest moons cast a shadow on the planet’s surface. An observer on an imaginary surface will be able to see a total solar eclipse.

Saturn

Multiple eclipses on Saturn

Seven of Saturn’s moons, including Titan, can occult the Sun. The planet’s axial tilt of 26 degrees render eclipses a rare occurrence.

Ice Giants

Uranus

Uranus, due to its peculiar way of moving around the Sun, can have eclipses once every 42 years. The last time this happened was in 2007-08. Twelve moons of Uranus are capable of eclipsing the Sun.

Neptune

Eclipses of the Sun from Neptune are rare due to the planet’s long orbital period and large axial tilt of 28 degrees. Unfortunately, we haven’t yet photographed an eclipse on Neptune.

The Beyond

Pluto

Simulated Plutonian eclipse

Pluto’s eclipses might be the most interesting. Charon, the largest of Pluto’s five moons, is roughly half the size of the parent planet. This immense size in addition to the fact that the sun is on average 5.9 billion kilometers away leads to the conclusion that the eclipses would be huge. They’re also rare though, the last Pluto – Charon eclipse is said to have happened in 1989, continuously for many days. Imagine a 6 hour blackout every day!

And that brings us to the end of this blog. If you found this interesting then don’t forget to share it with your friends. You can also suggest what I should write next in the comments section below. Until next time!

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