Mars at Opposition

Mars at Opposition

Mars just reached opposition, a time when it is in a straight line with the Earth and Sun. Mars therefore rises at sunset and is visible all night. It is also at its brightest, because usually opposition is also when the planet is at its closest approach to Earth and is fully illuminated, like a Full Moon.

Mars is presently located in Scorpius and as viewed from Earth is going through 'retrograde motion' in which the steady westward movement of the planet is temporarily interrupted by a reversal in motion back toward the east, as the Earth speeds past Mars in its orbit. The path of Mars in the background stars is nicely captured in this image from Naked Eye Planets and shows the retrograde path of Mars quite clearly.

Mars is easy to spot, a bright orange dot in the south that is grouped near another bright orange-red dot (in this case, Antares, the brightest star in Scorpius), and contrasting with a yellow-white dot that is Saturn.

Image courtesy Sky & Telescope

The Moon and Jupiter

Full Moon and Jupiter

Jupiter recently reached opposition, appearing at its brightest and traversing the night sky from sunset to sunrise. It's the most obvious beacon in the night sky, far outshining everything around it. That is, except for the Moon which of course is the brightest object in the night sky. This week as the Moon moves through its full phase, it has a close encounter with Jupiter on the evening of March 21.

By the way, since the Moon is full this week (on Wednesday March 23rd) just after the Spring Equinox, it will rise due East and set due West on that day, roughly mirroring the position of the Sun six months hence, on the Fall Equinox.

The King of the Night Sky

Jupiter has taken its place as the dominant object in the night sky, outshining everything else around it for the coming months. It just reached 'opposition' as it has its closest approach to the Earth for the next year. At opposition, Jupiter and the Earth and Sun are in a straight line, and Jupiter is visible for the entire night, rising in the east as the Sun sets in the west, towering high overhead during the night, and setting in the west just as dawn breaks.

Details of Jupiter

The disk of Jupiter is at its maximum visible size, a clear ball with dominant cloudtops in backyard telescopes, with the four moons visible every night in an interplay that changes hourly. It's one of my favorite telescope objects because there is so much richness and visual beauty in the sight of this giant planet with its equatorial bands shining through.

Take a moment to appreciate the King of the Night Sky, currently passing through Leo the Lion. Jupiter's orbit takes it around the Sun in 12 of Earth's years, so each year we see it move to the next zodiac sign (Cancer in 2014, Leo in 2015, and Virgo in 2016).

Image courtesy Sky & Telescope.

Saturn at Opposition 2013

Typical Telescope View of Saturn

Saturn reaches a special moment in the sky for us Earth-bound viewers, a time when conditions are most favorable for viewing the 2nd largest planet in the Solar System in all its glory. Opposition is the time when the planet is directly opposite the Sun, from our Earthly point of view. That means a few things: (a) it is at its closest to Earth, and therefore brightest for the year, (b) it is visible all night, rising just after sunset and setting just before sunrise, and (c) it is illuminated straight overhead from the Sun, much in the way we view a full moon.

For the city dweller, Saturn is an easy object to find, outshining most of the stars in the sky except nearby Arcturus, and its rival planet Jupiter (which is slowly fading into the west earlier each night). Saturn glows a yellow-white hue, in contrast to another nearby bright star, Spica. To find Saturn, it rises right after sunset this evening and for the foreseeable future, and glides from the south-east to the southern sky, and then across to the south-west after midnight.

If you have a telescope, now is the time to put it to work, as the view of Saturn will be at its finest. Wait a little while after sunset until Saturn is higher in the sky, less susceptible to atmospheric effects. The ring system is tilted 18 degrees toward Earth, so the view is quite good, and as anyone who has seen Saturn in a telescope will attest, the rings are amazing to see with your own eyes.

Here are two good resources for learning more about Saturn at opposition: Sky and Telescope's fine article, and EarthSky's tips how to find Saturn using the Big Dipper, Arcturus and Spica.

Image courtesy Wikimedia Commons

Jupiter at Opposition: Closest approach of the Year

Jupiter at Opposition

Every 13 months the planet Jupiter and Earth align with the Sun, a special moment called Opposition. That represents the closest approach between the two planets, and means that Jupiter is at its brightest and 'fullest' for the year. It's unmistakeable when it rises, the brightest light in the east after sunset, blazing in its glory in one of the most spectacular parts of the night sky, near the constellations Orion, Taurus and Auriga and a large number of bright, colorful stars.

It's easy to spot the four brightest Moons (also known as the Galilean Moons) of Jupiter if you use a simple telescope or binoculars. With Jupiter at opposition, now is the time to take a closer look. If you want to actually identify which Jovian moon is which, use this handy app from Sky & Telescope.

Image courtesy Space.com.

Mars at Opposition

Tonight Mars is at opposition, a once-every-25-month event in which Earth passes between the Sun and Mars, and we observe Mars at its closest approach. The patterns of alignments of the Earth with different planets is a very cyclical event, every year or two depending upon the proximity of Earth to that planet.

The relative distance from Earth to Mars at each opposition is also something that is quite cyclical. You might recall in 2003 claims that the "Mars is going to be as big as the full Moon" during that year's very favorable opposition. In fact, the disk of Mars was never that big, but hype aside, Mars appeared quite large compared to any other time in recent history. In 2012, opposition brings us Mars as a bright orange star in the east shortly after sunset, traveling across our night sky from horizon to horizon. Although it is at the closest until 2014, it is just a small dot of color through most home-based telescopes. You will need considerable power to see the polar ice caps and other surface features (such as in the photograph). My friends in the San Francisco Amateur Astronomers (SFAA) club live for such moments, and if you can visit a local observatory or visit a star party this time of year, I am sure Mars will be one of the highlights.

The next time Mars nears the size of its famous 2003 opposition is in 2018. Until then, enjoy Mars however big or small it looks. It's a fascinating planet.

Photo by Mark Killion.

Jupiter at Opposition -- closest approach for 2011

The Autumn evening sky is being dominated by one bright, shiny object: the planet Jupiter, which will be a highlight for several months in our skies. On October 28th, Jupiter reaches "opposition" in which it is in a line with the Earth and Sun (and no, that is not what has been causing the recent earthquakes in the San Francisco Bay Area!).

Image Courtesy NASA

When Earth travels around in its orbit, approximately every 13 months we have a close encounter with Jupiter. When we do, the gas giant looks impressive with or without a telescope. Without a telescope, Jupiter is extremely bright, easily 50 times brighter than the brightest stars in the sky right now. It rises due East just after sunset, and remains visible the entire night. Through a small amateur telescope, Jupiter is a fine target, easy to locate and impressive with bands across its disk and the four Galilean moons shining brightly. Now is the time to get out a telescope or binoculars and share the brilliance of Jupiter with someone.

Jupiter's closest approach to Earth

Today Jupiter is at its closest point to Earth for 2010, a mere 368 million miles. Although not a particularly astonishing event, it is nonetheless a prime time to get out your binoculars or telescope to view the giant planet as it dominates the night sky. Jupiter is a fun target to view up close because it offers so much to see: Four bright Moons, colors and textures from its cloud belts, and for a brief time right now it guides you to find the distant planet Uranus.

Every year as the Earth moves around the Sun, at some point in time it is at its closest approach to Jupiter. This moment is called "opposition" and is when the Earth, Sun and Jupiter are all in a perfect line. Each year the distance between the Earth and Jupiter might be a bit more or less depending upon the circumstances of each planet's orbit. This year, the distance is smaller than usual (closest since 1963 and until 2022), but that difference is relatively small from year to year. More important is that the planet is at its brightest for the year, and remains high in the sky for optimum viewing for the entire night.

Sky and Telescope Magazine has an excellent article about this close encounter if you want more details.

Mars and the Biggest Full Moon of 2010

The next few days offer a chance to see Mars and the full Moon together while each celestial body passes through its closest point to the Earth in their orbit. When Mars and Earth line up in their orbits around the Sun, we call that "opposition" and it represents the closest approach between the two planets. This takes place approximately every two years and when it does, Mars appears brighter than usual and is larger in a telescope. Also at opposition, Mars rises just as the Sun sets and is up all night. Mars is at opposition on Friday January 29th.

The Moon has an elliptical orbit around the Earth and as such, each orbital period (approximately 29 days) it is a bit closer to Earth (called Perigee) and then a bit farther from Earth (called Apogee) This month, the Moon is full and is at Perigee on the same date, Friday January 29th. It is also next to Mars so when you look outside on Friday evening, you'll be seeing a nice lineup of a couple of our nearest neighbors. When the Moon is at Perigee, it is a considerably bigger object in the sky than usual. The website Spaceweather.com highlights this nicely in their article.

I have written about the biggest full moon of the year in a previous blog post, if you want to get more information about that subject.

Regarding Mars and opposition, there was a great deal of hype in August 2003 when Mars had a particularly close opposition and was inaccurately stated as "being as big as the Full Moon." That won't ever happen, of course, but it certainly inspired a lot of people to take a look at Mars that summer. This week Mars will be less bright and big compared to 2003 but still a worthy binocular or telescope target. The next close encounter that will rival the 2003 lineup will be in 2018. For an extremely detailed chart and description of the Mars opposition phenomenon, visit the seds.org site.

Mars arrives in the evening sky

Mars is back on display, now visible shortly after sunset in the eastern sky. During the month of January it will reach "opposition" when it appears exactly opposite the Sun in the sky. At opposition Mars is also at closest approach to Earth (and is therefore at its brightest for the year). It shines a distinctive red-orange color especially when compared to the stars in Leo and Cancer that surround it. Through binoculars or a telescope Mars appears as a small colorful dot of light. This week the Moon serves as a guide for locating Mars.