Mercury what is it named after

What caused Mercury's crust to shrink? As the interior of the planet cooled it contracted. Gravity then forced the crust to adjust to a smaller interior. Another large lobate scarp on Mercury is Discovery Rupes. Rupes is Latin for cliff. Discovery is about kilometers miles long and up to 1. Notice that the walls and floors of two impact craters have been deformed by the thrust fault that formed the scarp.

How do we know how high Discovery Rupes is? One way is to use two images that provide a stereo 3-D view of the feature. Using a computer, the heights elevations of all the points covered by a stereo pair can be calculated and a digital elevation model made. This Mariner 10 image shows the area covered by the stereo pair and the digital elevation model is color-coded to show the highest elevations in white and lowest elevations in black.

The white arrows in the image indicate the location of part of Discovery Rupes. Between the heavily cratered regions of Mercury's surface lie large expanses of smooth plains.

Venus's dense atmosphere causes a greenhouse effect, resulting in higher temperatures. Mercury's orbit is elongated, taking an almost oval- or egg-shaped course around the Sun. This means that its distance from the Sun varies throughout its circuit, between approximately 46 million and 70 million kilometres.

Days on Mercury are very long because the planet rotates very slowly. One day-long spin lasts for 59 Earth days. But because of its fast orbit, one Mercury year takes 88 Earth days. This means that two years on Mercury lasts for only three days. The planet's sunrise would be unusual to us on Earth.

Due to its elongated orbit and slow rotation, from some places on Mercury's surface, the Sun appears to rise briefly before setting and rising again. At sunset, the reverse happens, with the Sun appearing to set twice. The planet spins almost vertically on its axis, so its poles are never fully sunlit. The lack of tilt also means that the planet does not experience yearly seasons like Earth. This model projects what the northern pole of Mercury may look like. The planet's vertical spin means that the pole is never fully sunlit.

Mercury has little atmosphere, but what it does have is made up mostly of oxygen, sodium, hydrogen, helium and potassium. The thin atmosphere, or exosphere, does little to prevent or slow down impacts from extraterrestrial objects, leaving the surface littered with craters. In appearance it is similar to Earth's Moon. Since Mercury was visible with the unaided eye, most of the ancient cultures had their own name for Mercury. The ancient Babylonians called the planet Napu, after a god in their mythology.

It is about the size of the continental United States, slightly bigger. It has a mass of about 3. Despite being the smallest planet from the Solar System, it is the second densest planet in the Solar System , with a density of 5.

Mercury's highly eccentric, egg-shaped orbit takes the planet as close as 29 million miles or 47 million kilometers, and as far as 43 million miles or 70 million kilometers from the Sun. Mercury travels through space at nearly 29 miles or 47 kilometers per second, faster than any other planet. The resonance makes a single solar day on Mercury last exactly two Mercury years, about Earth days. Radar observations in proved that the planet has a spin—orbit resonance, rotating three times for every two revolutions around the Sun.

The eccentricity of Mercury's orbit makes this resonance stable at perihelion, when the solar tide is strongest. The Sun is nearly still in Mercury's sky. The orbital eccentricity of Mercury in simulations varies chaotically, from zero or circular to more than 0. More accurate modeling based on a realistic model of tidal response has demonstrated that Mercury was captured into the spin—orbit state at a very early stage of its history, within 20 or 10 million years after its formation.

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 a sunrise and sunset like on most other planets. The morning Sun appears to rise briefly. It then sets and rises again from some parts of the planet's surface.

The same thing happens in reverse at sunset for other parts of the surface. The axial tilt is almost zero, with the best measured value as low as 0. This is significantly smaller than that of Jupiter , which has the second smallest axial tilt of all planets at 3. On average, Mercury is the closest planet to Earth, and to each of the other planets in the Solar System. Interestingly, many of these craters are named after famous deceased artists and authors. There are also extensive mare-like plains present and the craters also indicate that the planet has been geologically inactive for billions of years.

It is believed that Mercury was heavy bombarded by comets and asteroids during and shortly after its formation 4. It is believed that Mercury was volcanically active during this period. Basins such as the Caloris Basin were filled with magma, producing smooth plains similar to the lunar marias found on the Moon.