An open southern vista is essential, because 20 degrees is lower than many trees and buildings. This is the best time to view the planet in a telescope, because it will then be shining through less of Earth's distorting atmosphere. local time, when it will reach an elevation of about 20 degrees (or two outstretched fist diameters) above the southern horizon. A few days before opposition, Mars will rise in the east at about 9:35 p.m. Here's how to find and see Mars this week. At that distance, it will take only 3 minutes and 18 seconds for radio signals to reach Mars. At that time, the Red Planet will be 35.79 million miles (57.6 million km), or 0.385 astronomical units, from Earth. (Image credit: SkySafari App)īecause both Earth and Mars will be continuing to run their "race" after opposition night, and Mars' perihelion date isn't until mid-September, our actual minimum distance from Mars will occur on the night of Tuesday, July 31. The close approach of July 27, 2018, will not reoccur until 2035. The two planets are closest when oppositions fall between Earth's aphelion (green A) and Mars' perihelion (brown P). The radiating lines show the oppositions of Mars from 2012 through 2025. This schematic of the inner solar system as viewed from far above the sun's north pole shows the nearly circular orbit of Earth (green) and the more elliptical orbit of Mars (brown). To the naked eye, the planet will still look like a bright-red pinpoint of light.) That's about two-thirds the size of Jupiter! (Don't be misled by the popular Internet meme that suggests Mars will appear as large as the full moon. At that time, Mars will shine more brightly than any planet except Venus and show a disk that is 24.2 arc seconds across. Eastern Daylight Time (0500 GMT) on Friday, July 27. The 2018 Mars opposition occurs at 1 a.m. And because we are closer to it, it will shine more brightly than at any other date and appear larger in binoculars or a telescope. That planet will rise in the east as the sun sets in the west. When Earth passes a more distantly orbiting planet on the "inside track," that planet's position in our sky will be opposite the sun - a term astronomers call opposition. Try that one, too the two planets will be slightly farther apart. The next Mars opposition date will be Oct. Earth returns to the same location, but Mars will jump to the opposite side of the sun. For fun, advance the date one year hence to July 27, 2019. (The time of day isn't important.) Now you can see the shapes of the orbits and how Earth and Mars line up with the sun and with one another. Open the Time Flow control panel and set the date to July 27, 2018. Use the upward pointing arrow at the lower right of the main screen to zoom in on the inner solar system until the orbit of Mars fills the display. If the planet orbits aren't displayed, enable them in the Settings/Solar system menu by tapping the Show Planet Orbits option. The app will position you above the plane of our solar system. In SkySafari 5 for Android or SkySafari 6 for iOS, find and select the sun, then tap the Orbit icon. You can demonstrate how Earth and Mars are arranged at opposition using your astronomy app. A year from now (right panel), Earth will return to the same position, but Mars will be on the far side of the sun from Earth, having only completed half of an orbit. On J(left panel), Mars will reach opposition for 2018, when Earth will pass between the Red Planet and the sun. We have not been this close to Mars since 2003 and won't be again until 2035! When that happens, our two planets are at their minimum separation from one another. Every 15 years or so, the geometry works out that we pass Mars while we are near aphelion (our maximum distance from the sun) and Mars is near perihelion (its minimum distance from the sun). Its distance from the sun varies quite a bit - between 128.4 million miles (206.7 million kilometers) and 154.8 million miles (249.2 million km), or about 20 percent. Our orbit is fairly circular, while Mars' orbit is much more elliptical. To be precise, Earth passes Mars every two years and 50 days. When Earth completed its second lap, Mars would be back on the same side of the sun and a bit ahead of us along the track. If the planets were placed at the same starting line on an imaginary racetrack around the sun (as they will be this Friday), when Earth returned after one lap, slowpoke Mars would be out of sight on the opposite side of the sun. In fact, Earth circles the sun almost two times in the time Mars takes to complete one orbit. That causes Earth to complete an orbit of the sun faster than Mars does. Mars has an orbit that is about 50 percent farther from the sun than Earth's, on average.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |