Planetarium Newsletter - May 2018

Cosmic Curiosities

“The most exciting phrase in science is not ‘Eureka!’ but ‘That’s funny…’”
~ Isaac Asimov, American Scientist & Author


Two Startling Surprises from Space

that's funny cartoon

One of the joys of science is the unexpected -- those “that’s funny” moments that makes scientists scratch their heads in disbelief. They trust their methods, experiments, and observations, but what they find seems to come from out of the blue -- and often a discovery is messy, meaning there’s no immediate explanation.

To be sure, not all discoveries are surprises. Countless times, a scientist says, “I know this about ‘A’ so ‘B’ must be there,” and they are spot on. For example, take the discovery of Neptune in 1846; astronomers noticed Uranus was off-track. They deduced another planet’s gravity was the culprit. They did the math and the calculations said, “Point your telescope there.” And, lo and behold, Neptune was there!

Below are two surprise discoveries from space. There are countless more, obviously, but we’ll start here.

1. Galileo’s New Universe

galileo galilee

Galileo had no idea what he would discover with his new telescope. But his findings changed the world. The Renaissance-Italian saw moons were circling Jupiter -- a staggering result because it showed not everything orbited the Earth.

On our Moon, Galileo spotted numerous craters. On the Sun’s surface, he saw changing black blemishes. The observations were telling Galileo that the objects in the sky were not perfect — as most people believed at the time.

Though surprising and unexplainable, Galileo trusted what he saw. The bigger shock came from the many people who did not believe Galileo’s results. His new book, Sidereus Nuncius (or Starry Messenger), published in 1610, convinced some but many saw it as heresy. They considered his telescope faulty or that Galileo was “seeing” things.

It took awhile, but eventually, better telescopes and similar discoveries helped people realize the universe above them was dynamic -- that it had physical forces like those on Earth. People also came to understand that the Earth truly does orbits the Sun — one of Galileo’s main principles. But again, these awakenings were slow and most occurred long past Galileo’s time. Near the end of his life, we went on trial for advancing his theory that the Earth revolves around the Sun. In 1633, Galileo agreed not to teach his view and spent his last nine years under house arrest.

2. The Speed of Light Limit

At first glance, everyone saw light as instantaneous. It’s obvious -- an everyday experience. Galileo’s genius led him to think light might be finite. He tried an experiment, but he couldn’t produce any evidence.

In 1676, after observing Jupiter’s moons eclipsing behind the big planet, Danish astronomer Ole Roemer became the first person to measure the speed of light. It wasn’t the precise result we have today, but it was close enough given the tools he had. While Roemer’s result was a surprise, the more shocking realization was that nothing could go faster than the speed of light.

einsteinThink of it this way: A phenomenal pitcher in baseball throws the ball 100 miles per hour; if the player happens to be on a blisteringly fast spaceship going 25,000 miles an hour and then threw the ball, its speed would increase to 25,100 miles an hour. Makes sense, right?

Now, imagine shooting a beam of light on the spaceship, instead of throwing a baseball. The speed of light is 186,282 miles per second. In this scenario, would the light beam travel faster, like the baseball did in the previous example? If you add the two speeds — light speed and the spaceship speed (25,000 mph ≈ 7 miles per second) -- you get 186,289 miles per second. But that answer is wrong! The speed of light stays constant, it has a precise limit — and nothing can go faster.

This startling discovery started with Albert Michelson in the 1880s in Cleveland, Ohio, not Albert Einstein. Michelson measured the speed of light and the velocity of the Earth as it orbits the Sun. He found the speed of light was constant no matter which way he shot his beam of light. This led some to think the Earth wasn’t moving; but his results were known by Einstein, who had wondered about traveling as fast as light and what the universe would look like. It led to his declaration that nothing can go faster than light, as part of his theory of special relativity in 1905.


Where Does Space Begin?

the space line

Does space start at 50 miles up? A hundred miles? A thousand?

How about 62?

A privately financed American manned rocket, SpaceShipOne, successfully flew into space and returned to Earth. It was reported that "the ship crossed the official 62-mile-high border of space."  Is that the official marker between sky and space?

Why 62? Since the U.S. never really went metric, 62 miles sounds strange. But when we realize it equals 100 kilometers, and 100 is a nice, round number, 62 works! It was chosen by the World Air Sports Federation (FAI) in the 1950s. Their leader said the choice was "fairly arbitrary," but is backed up by science.

In the ‘50s, the space age was coming on fast. The first satellite came with the USSR’s Sputnik in 1957. The first astronauts flew in 1961. People needed a boundary between where aeronautics ended and astronautics began. A group of aeronautics researchers, led by Hungarian Theodore Von Karman, tried to predict the altitude below which significant lateral thrust would be required to keep a craft flying level. The group speculated that this would happen somewhere around 100 kilometers, so Von Karman suggested the federation just use that nice, round number everyone could agree upon. The 100-kilometer standard, sometimes called the Karman Line, has since been adopted by many agencies and organizations worldwide.

The National Aeronautics and Space Act, which created NASA in 1958, simply defines space as "outside Earth's atmosphere." But it's tricky to pinpoint where the Earth's atmosphere ends. NASA could use a figure as lofty as 600 kilometers, or 373 miles, as the outer limit of the upper atmosphere, or thermosphere, high above the International Space Station, which generally orbits about 354 kilometers, or 220 miles, above sea level. Or, it could say space begins 50 kilometers up, or 31 miles, at the top of the stratosphere, below which one finds 99 percent of the air in the atmosphere. But when determining who is an astronaut, NASA uses the FAI's 100-kilometer figure. The U.S. Air Force, however, awards astronaut wings to rated officers who fly higher than 50 miles (or about 80 kilometers) above sea level.


Four Stars for Mars

mars core gifMars will make headlines soon — and then again this summer! Here are four stars justifying why.

InSight on Mars

Very soon, as early as May 5, NASA will launch another robot explorer to Mars. It called InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport). Whew. . . . That’s a hard one to remember, but NASA likes their acronyms.

InSight is a lander; no wheels this time. If all goes well, it will touch down in late November 2018, around Thanksgiving. The launch will be from Vandenberg Air Force Base in California and could be seen by millions. It’s the first planet mission to launch from California.

Mars's InSight will search deep inside the red planet, looking for clues about how it formed.  Instruments are designed to record seismic movements. InSight will also study the different layers of Mars, including its crust, mantle, and core.

satellite signals★★ Wall-E and Eva

Wall-E and Eva are heading to Mars with InSight. They are the nicknames for two little satellites that are part of Mars Cube One, or MarCO. Also called CubeSats, their collective goal is to speed up communications between Earth and Mars when InSight lands. Currently, NASA often has to wait until everything is aligned perfect to communicate in real-time. If Wall-E and Eva survive the trip, and work as expected, the communications could happen in real-time. Of course, Mars is millions of miles away, so light speed has to be taken into consideration. Light, or radio signals, from Mars take about three minutes at its closest to Earth, and 22 minutes when the red planet is at its farthest point.

★★★ Did Mars Get Sideswiped like Earth?

phobos and deimos

A huge impact is the leading origin theory for Earth’s Moon. Billions of years ago, our planet was pummeled by a mammoth, Mars-sized rock. The impact debris formed a ring around our planet that eventually condensed into our Moon.

Did the same thing happen on Mars? The two little Moons of Mars are called Phobos (god of fear) and Deimos (god of terror). Their diameters are only 14 miles and 7.5 miles respectively. They look like asteroids, so they must have been captured asteroids -- which makes sense, because the asteroid belt is located nearby. However, the orbits of these asteroid-looking moons are nearly circular. If they were captured asteroids, the orbits would be more elliptical.

We know Earth’s Moon came from an impact because of the moon rocks. The rocks resemble Earth mantle that was torn off by the impact. This means that the only sure way to know the origin of the Martian moons is to bring back some rocks. The Japan Aerospace Exploration Agency (JAXA) hopes to launch a mission in 2024 that will collect samples of the moon Phobos and return to Earth in 2029.

mars and earth orbits★★★★ Summer Spotlight on Mars

In 2003, Mars was closer and brighter in our sky than in nearly 60,000 years. On July 31, 2018, Mars will be at its brightest since then!

The changing brightness of Mars in our skies is dramatic. In late July 2018, the red planet will be 40 times more brilliant than last autumn. It will be almost twice as bright as Jupiter. The main reason for dim and dazzling Mars is distance. As Earth and Mars orbit the Sun, every 2.2 years they line-up on the same side and are at their closest. This near proximity changes, too, because of their elliptical orbits. In August 2003, the two rocky worlds were closer than they’ve been in nearly 60,000 years. This July, Mars will be at its brightest best since then — almost 15 years later!

Sky Sights


Venus is even easier to see this May. By the end of the month, the hottest planet sets about 2.5 hours after sunset. A gorgeous crescent Moon orbits by from May 17-19.

may sky

Jupiter is at opposition on May 8. This is when the Sun, Earth, and Jupiter form a straight line. As the Earth spins into nighttime, Jupiter rises. As we spin back toward the Sun, Jupiter sets. Opposition also means Jupiter shines at its brightest! Spot the Moon nearby from May 25-27.

may sky may sky

Mars rises after midnight all month. Watch Mars grow brighter slowly each night. In late July, the red planet will be brighter than it has been in 15 years! Look for the Moon very close on May 6.

Saturn separates from Mars this month by an hour. At the start of the month, the ring jewel rises about an hour before Mars. At the end of May, it rises two hours earlier—a little after 10:00 p.m. CDT.  The Moon passes Saturn twice in this month: May 4-5 and May 30-31.

Mercury is too close to the Sun to see all month.

Star Map

Download the May Star Map. >> 

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