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Starts With A Bang

Watch Saturn, Mars, And Jupiter All Meet In March 31, 2020’s Pre-Sunrise Skies

On the morning of March 31, 2020, these three worlds will be at their mutual closest in 20 years.

For the past few weeks, Mars, Saturn, and Jupiter have all shone prominently in the pre-sunrise skies.

During the month of March, 2020, the three outer naked-eye planets, Saturn, Jupiter and Mars, all clustered together in the pre-sunrise skies. On March 18, they were joined by the waning crescent Moon. (Gary Hershorn/Getty Images)

As the only naked-eye planets orbiting exterior to Earth, they’ve all lined up numerous times this month.

On March 04, 2020, the planets Saturn, Jupiter, and Mars all appeared in an equally spaced line. Throughout the month, both Saturn and Jupiter have experienced relative apparent motion in our skies, but Mars has moved the fastest from west to east, passing between Jupiter and Saturn and eventually moving even eastward of Saturn. (E. SIEGEL / STELLARIUM)

On March 4, 2020, they were equally spaced, with 8° separating each of these three outer planets.

By March 26, 2020, Mars had moved a total of approximately 12 degrees in the sky relative to its March 4 position, continuing its eastward migration and placing it roughly mid-way between Saturn and Jupiter. (E. SIEGEL / STELLARIUM)

On March 26, 2020, just three weeks later, they were equally spaced more tightly, with just 3.5° of mutual separation.

The heliocentric model of the Solar System (R), along with Kepler’s/Newton’s laws, predicts that inner planets will orbit at faster speeds than progressively outer planets, explaining their apparent motions through the sky. The fact that planets are at different distances and move at different relative speeds with respect to Earth explains why these apparent celestial motions occur. (E. SIEGEL / BEYOND THE GALAXY)

The fact that planets are located at different distances from the Sun ensures that they move at different speeds.

When we place the known objects in the Solar System in order, four inner, rocky worlds and four, outer, giant worlds stand out. While fast-moving Mercury, the innermost world, takes just 88 Earth days to complete a revolution around the Sun at its speed of 47 km/s, outermost Neptune takes over 160 years, moving at just 5.4 km/s. (NASA’S THE SPACE PLACE)

This is why the separation and even the order of these worlds changes, from our perspective, over time.

An accurate model of how the planets orbit the Sun, which then moves through the galaxy in a different direction-of-motion. Note that the planets are all in the same plane, and are not dragging behind the Sun or forming a wake of any type. The planets change position relative to one another, making them change their apparent positions and brightnesses in the sky as seen from Earth. (RHYS TAYLOR)

In the pre-dawn skies of March 31, 2020, skywatchers globally will be treated to a spectacular alignment.

In the pre-dawn hours on the morning of March 31, 2020, Mars and Saturn will make a very close approach to one another, coming within 0.9 degrees of each other, while Jupiter remains farther away at about 6 degrees separation from the close pair. (E. SIEGEL / STELLARIUM)

First off, Mars and Saturn will experience a conjunction, separated by just 0.9°.

Mars, Jupiter and Saturn can often be seen together in the night sky, but only rarely do all three of these worlds cluster together. They also vary in brightness by large amounts. In March of 2020, Jupiter will be much brighter than either Mars or Saturn, which are somewhat comparable to one another, in contrast to this 2018 image, where Mars (at left) and Jupiter (at right) were both very bright, but Saturn (near the center) was much fainter. (VW Pics/Universal Images Group via Getty Images)

Jupiter remains close by, located approximately 6° away from the close pair, making them easier to spot.

The seven extraterrestrial planets of the solar system: Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune. Photographed in 2019 with a Maksutov telescope from Mannheim and Stockach in Germany. The angular sizes and colors shown are accurate, but the brightnesses are not: Venus is some 63,000 times brighter than Neptune, or 12 astronomical magnitudes; the same difference as between the full Moon and a typical bright star like Vega or Capella. (GETTY IMAGES)

Through a telescope, all three of these worlds will appear in their nearly-full phase, as demanded of outer planets.

If you were to hold up your little finger at arm’s length on the morning of March 31, 2020, Mars and Saturn will be separated by merely the width of your pinkie’s fingernail, the closest approach of these two worlds since 2008. (E. SIEGEL / STELLARIUM)

It’s a prelude to December 21, 2020’s Great Conjuction, where Saturn and Jupiter meet in the post-sunset skies, just 0.06° apart.

On the night of December 21, 2020, Jupiter and Saturn will appear so close to one another, just 0.1 degrees apart, that these two worlds and many of their moons will be visible in the same field-of-view of a relatively high magnification telescope. This will be one of the most spectacular astronomical events of the decade. (ASTRONOMY CLUB OF ASHEVILLE / ASTROASHEVILLE.ORG)

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.

Ethan Siegel is the author of Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.


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