Mars Gears Up For Its Closest Approach To Earth In Over A Decade

Mars gears up for its closest approach to Earth in over a decade

“Relative to the stars in the sky, planets generally move slightly towards the east from night-to-night. But beginning tonight, Mars will move to the west, commencing retrograde motion, which continues until June 30th. This isn’t due to Mars changing its motion, but rather to Earth, orbiting inner to Mars, overtaking it due to Earth’s faster path around the Sun.”

Every two years, Earth passes Mars in orbit, as the inner, faster world overtakes the outer one. This year, it happens when Earth approaches aphelion, its farthest point from the Sun, while Mars approaches perihelion, or its closest approach. On May 30th, the two worlds pass within just 0.51 A.U. (76 million km) of one another, their closest encounter since 2005. While Mars will still appear as no more than a point to unaided human vision, telescopes will provide absolutely spectacular views during the next three months. If you miss it, you’ll have to wait two years for views this good, and then you won’t get them again until 2035.

Go get the whole story – and some amazing pictures – to start your week off right!

Leap Day…Why Does It Exist?

Once every four years, an extra calendar day is added: a leap day. But why?

The reason for adding leap days to the calendar is to align the calendar year with the actual year – which is defined by the time it takes Earth to circle the sun. It is equal to 365 days, 5 hours, 48 minutes and 46 seconds, or 365.24219 days.

If all calendar years contained exactly 365 days, they would drift from the actual year by about 1 day every 4 years. Eventually, July would occur during the northern hemisphere winter! Wouldn’t that be weird?

To correct (approximately), we add 1 day every 4 years…resulting in a leap year.

By making most years 365 days but every fourth year 366 days, the calendar year and the actual year remain more nearly in step.

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allisonkitten

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Moon+Saturn

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allisonkitten

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Worlds That Will Make You Believe Star Wars is Real

The fantastical planets in Star Wars preceded our discovery of real planets outside our solar system…but fiction isn’t too far from the facts. When we send our spacecraft into the solar system and point our telescopes beyond, we often see things that seem taken right out of the Star Wars universe.

Is there a more perfect time than May the 4th to compare real worlds to the ones depicted in Star Wars?

Probably not…so here are a few:

Mimas

Saturn’s moon, Mimas, has become known as the “Death Star” moon because of how its 80-mile wide Herschel crater creates a resemblance to the Imperial battle station, especially when seen in this view from our Cassini spacecraft.

Kepler-452b

The most recently revealed exoplanet dubbed as Earth’s bigger, older cousin, Kepler-452b, might make a good stand-in for Coruscant — the high tech world seen in several Star Wars films whose surface is encased in a single, globe-spanning city. Kepler-452b belongs to a star system 1.5 billion years older than Earth’s! That would give any technologically adept species more than a billion-year jump ahead of us.

CoRoT-7b

At 3,600 degrees Fahrenheit, CoRoT-7B is a HOT planet. Discovered in 2010 with France’s CoRoT satellite, it’s some 480 light-years away, and has a diameter 70% larger than Earth’s, with nearly five times the mass. Possibly the boiled-down remnant of a Saturn-sized planet, its orbit is so tight that its star looms much larger in its sky than our sun appears to us, keeping its sun-facing surface molten! This scorching planet orbiting close to its star could be a good analog for planet Mustafar from Star Wars.

Kepler-16b

Luke Skywalker’s home planet, Tatooine, is said to possess a harsh, desert environment, swept by sandstorms as it roasts under the glare of twin suns. Real exoplanets in the thrall of two or more suns are even harsher! Kepler-16b was the Kepler telescope’s first discovery of a planet in a “circumbinary” orbit (a.k.a, circling both stars, as opposed to just one, in a double star system). This planet, however, is likely cold, about the size of Saturn, and gaseous, though partly composed of rock.

OGLE-2005-BLG-390

Fictional Hoth is a frozen tundra that briefly serves as a base for the hidden Rebel Alliance. It’s also the nickname of real exoplanet OGLE-2005-BLG-390, a cold super-Earth whose surface temperature clocks in at minus 364 degrees Fahrenheit.

Kepler-22b

Kepler-22b, analog to the Star Wars planet Kamino…which was the birthplace of the army of clone soldiers, is a super-Earth that could be covered in a super ocean. The jury is still out on Kepler-22b’s true nature; at 2.4 times Earth’s radius, it might even be gaseous. But if the ocean world idea turns out to be right, we can envision a physically plausible Kamino-like planet.

Gas Giants

Gas giants of all stripes populate the real exoplanet universe; in Star Wars, a gas giant called Bespin is home to a “Cloud City” actively involved in atmospheric mining. Mining the atmospheres of giant gas planets is a staple of science fiction. We too have examined the question, and found that gases such as helium-3 and hydrogen could theoretically be extracted from the atmospheres of Uranus and Neptune.

Exomoons

Endor, the forested realm of the Ewoks, orbits a gas giant. Exomoon detection is still in its infancy for scientists on Earth. However, a possible exomoon (a moon circling a distant planet) was observed in 2014 via microlensing. It will remain unconfirmed, however, since each microlensing event can be seen only once.