Few things in space are as sloppy as a solar system—and few solar systems are as sloppy as ours. That can be a very good thing if you like cosmic sky shows, because now and again, the familiar nighttime heavens can change in dramatic ways. Heathkit hm 102 manual. Monday will be one of those times, when Mars makes an unusually close pass by Earth, drawing nearer—and looming larger—than at any time since 2005.
Here’s what’s behind the cosmic coziness:
The orbit any planet makes around its parent star is fixed and knowable. Earth takes 365.256 days to make a single lap around the sun. (The 365 part is how we measure our year, and the .256 is why we tack on an extra day at the end of February every four years.) For Mars, a year is 686.93 days. For Neptune—well, a single Neptunian year takes 164.79 Earth years.
Orbit and Rotation As Mars orbits the Sun, it completes one rotation every 24.6 hours, which is very similar to one day on Earth (23.9 hours). Martian days are called sols—short for 'solar day.' A year on Mars lasts 669.6 sols, which is the same as 687 Earth days. Orbit of Mars Mars has an orbit with a semimajor axis of 1.524 astronomical units (228 million kilometers), and an eccentricity of 0.0934. The planet orbits the Sun in 687 days and travels 9.55 AU in doing so, making the average orbital speed 24 km/s.
Those different orbital speeds mean that the distance between any two planets is always changing. As Earth zips around in the solar system’s No. 3 lane, for example, it sometimes finds itself on the complete opposite side of the sun from Mars, putting the two planets as much as 249 million miles (401 million km) apart. Every other year, however, Earth laps Mars, overtaking its pokier sister and bringing the two planets briefly as close as 33.9 million miles (54.6 million km). It’s during those biannual windows that NASA typically launches its missions to Mars, keeping the travel time from one planet to the other to a minimum.
Not all close encounters between Earth and Mars are equal, however. Few planets in any solar system orbit their suns in a perfect circle. Instead they follow a slightly egg-shaped path, which means that each orbit has a perihelion (closest approach to the parent star) and an apehelion (farthest approach). Mars’ closest approach to the sun is 128.4 million miles (206.6 million km) and its furthest is 154.8 million mi. (249.2 million km). For Earth, the perihelion is 91.4 million miles (147.1 million km) and the apehelion is 94.5 million miles (152.1 million km).
And things get messier still. Planets don’t typically orbit perfectly in the flat, circling neatly around a star’s equator. Most are slightly inclined relative to that midline, moving above their sun’s equatorial plane at one part of their orbit and below it at another. Mars’ orbit is inclined 5.65 degrees relative to the Sun’s equator; Earth’s is a slightly more drunken 7.155 degrees.
For two planets to make an especially close approach like Mars and Earth are about to do, it means that the inner planet (Earth in this case) must be in its apehelion phase (cheating a bit away from the sun) when it passes Mars; and that Mars must be in its perihelion phase (cheating in). It also means that the planets must be close to one another in inclination to the sun, with both above the solar equator or both below it.
All of that is now lining up, with Mars and Earth set to pass each other at a relative shouting distance of 46.8 million miles (75.3 million km) on Monday, and even casual skywatchers will notice the difference without the aid of a telescope. Most of the time, Jupiter is the brightest object in the nighttime sky after the moon, but Mars will rival it in brilliance until June 3.
If you like what you see this week, you’ll love it in 2018—on July 27 of that year specifically. Mars is approaching the low point in its perihelion cycle now, but it’s not quite there yet, and Earth will have sped past already when it does reach that nadir. In 2018, we’ll pass Mars when it’s closer still to that low point, bringing the two planets just 35.8 million miles (57.6 million km) apart—about 24% closer than they’ll be this week.
Serif photo. And that is plenty close, thank you very much. About 4.5 billion years ago, the primordial Earth suffered a near-death experience when a rogue Mars-sized planetesimal collided with it, sending up a debris cloud that is thought to have been the raw material for the moon. The actual Mars is not about to jump its orbital lane and come careering our way.
But in a solar system born in violence, it’s always nice if very close encounters never become too close.
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For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.Most people are familiar with Earth's orbital pattern, so it is easiest to discuss Mars's orbit as it relates to Earth's. Mars and Earth share many similarities in their orbits. They are both elliptical patterns and are held on a similar axial tilt. Mars's orbit has a more eccentric pattern than Earth, which introduces some differences in weather patterns between the two planets.
If viewed from above, both Earth and Mars appears to orbit the sun in a counterclockwise direction and are nearly on the same plane. An Astronomical Unit is a measurement of approximately 150 million km, or the distance from Earth to the Sun. Earth's orbit is therefore 1 Astronomical Unit (AU), while Mars averages 143 million miles (230 million km) or 1.5 AU. It takes Earth one year to orbit the sun, while a Mars orbit clocks in at about 687 Earth days or 1.88 times as long as an Earth year. A Mars day is slightly longer than an Earth day, averaging about 24 hours, 39 minutes, and 35 seconds.
Mars Orbit Time
Eccentricity is used to define the shape of any planetary orbit. A perfect circle has an eccentricity of zero. Ellipses have an eccentricity between 0 and 1, while parabolas have an exact measurement of 1. Mars's orbit has an eccentricity of 0.09, which makes it the second most eccentric orbit of all the planets. Only Mercury has a greater one.
Mars Orbit Au
This eccentricity means that there is a big difference in distances from when it is closest to the Sun, or its perihelion, and when it is furthest away, the aphelion. The perihelion on the Mars orbit is approximately 1.38 AU or 129 million miles (207 million km.) The aphelion is about 1.66 AU or 155 million miles (249 million km.)
Mars Orbit
Mars's axial tilt is 25.19 degrees. Since this is very similar to the Earth's tilt of 23.45 degrees, Mars's seasons are very similar to those on Earth in that there are four. Each season lasts nearly twice as long as an Earth season since the Mars year is longer. They also tend to be much more extreme since the aphelion and perihelion are so drastically different. Summers are hotter since Mars's orbit comes closer to the sun, while winters are harsher in its furthers reaches.
Where Is Mars Right Now
It is presumed that many years ago, Mars's orbit was much less eccentric. It is estimated to have been closer to 0.002 about 1.35 million Earth years ago. The gravitational forces created by the other planets have been slowly pulling Mars into a greater elliptical pattern.