Like Earth, each planet in the solar system technically has four seasons. A planet with no tilt and a perfectly circular orbit around the sun will cop sunlight along the equator at all times.
Throw in characteristics such as atmosphere, orbit, distance from the sun and how many hours are in each day, and the intensity of any given season changes too. Earth is also lucky enough to have a near-circular orbit, which keeps the overall climate steady and our seasons pretty much comparable between years.
For a planet with an elliptical orbit, changes in distance from the sun can cause massive seasonal fluxes in temperature.
Mercury is also the only planet in our solar system without any tilt, so technically lacks seasons. But what it does have is a highly elliptical orbit, creating a version of summer and winter. Venus has a similar size and density to Earth. Venus is tilted too, but at a minuscule 2. The smallest planet in our solar system and nearest to the Sun, Mercury is only slightly larger than Earth's Moon.
From the surface of Mercury, the Sun would appear more than three times as large as it does when viewed from Earth, and the sunlight would be as much as seven times brighter. Mercury's surface temperatures are both extremely hot and cold. Despite its proximity to the Sun, Mercury is not the hottest planet in our solar system — that title belongs to nearby Venus, thanks to its dense atmosphere.
But Mercury is the fastest planet, zipping around the Sun every 88 Earth days. Mercury's environment is not conducive to life as we know it. The temperatures and solar radiation that characterize this planet are most likely too extreme for organisms to adapt to.
If Earth were the size of a nickel, Mercury would be about as big as a blueberry. From an average distance of 36 million miles 58 million kilometers , Mercury is 0. One astronomical unit abbreviated as AU , is the distance from the Sun to Earth. From this distance, it takes sunlight 3.
Mercury's highly eccentric, egg-shaped orbit takes the planet as close as 29 million miles 47 million kilometers and as far as 43 million miles 70 million kilometers from the Sun. It speeds around the Sun every 88 days, traveling through space at nearly 29 miles 47 kilometers per second, faster than any other planet. Mercury spins slowly on its axis and completes one rotation every 59 Earth days.
But when Mercury is moving fastest in its elliptical orbit around the Sun and it is closest to the Sun , each rotation is not accompanied by sunrise and sunset like it is on most other planets. The morning Sun appears to rise briefly, set, and rise again from some parts of the planet's surface.
The same thing happens in reverse at sunset for other parts of the surface. One Mercury solar day one full day-night cycle equals Earth days — just over two years on Mercury.
Mercury's axis of rotation is tilted just 2 degrees with respect to the plane of its orbit around the Sun. That means it spins nearly perfectly upright and so does not experience seasons as many other planets do.
Mercury formed about 4. Like its fellow terrestrial planets, Mercury has a central core, a rocky mantle, and a solid crust. Mercury is the second densest planet, after Earth. It has a large metallic core with a radius of about 1, miles 2, kilometers , about 85 percent of the planet's radius. There is evidence that it is partly molten or liquid. But this only true at the poles, where the floors of deep craters are never exposed to direct sunlight, and temperatures within them therefore remain below the planetary average.
These icy regions are believed to contain about 10 14 —10 15 kg 1 to 10 billion metric tons, 1. Over the course of two years, that weather will remain scorching hot or freezing cold. Between its rapid and very eccentric orbit, its slow rotation, and its strange diurnal and annual patterns, Mercury is a very extreme planet with a very extreme environment.
It only makes sense that its weather would be similarly extreme. We have written many interesting articles about the weather on other planets here at Universe Today.
Listen here, Episode Mercury. Skip to content.
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