Planetarium Newsletter - June 2017

Cosmic Curiosities

“Nobody is bored when he is trying to make something
that is beautiful, or to discover something that is true.”

~ William Ralph Inge, American Author

A Grand Finale at Saturn

Who doesn’t love a cool image of Saturn and its rings?

This is Saturn’s dark side -- the Sun is directly behind it. This green infrared snapshot is color-coded by temperature. Photos like this help scientists see Saturn in different ways, leading to a better understanding of the ring-world.

The stunning imagery from Saturn will come to an end, however, on September 15, 2017. After 12 years orbiting Saturn, NASA’s Cassini spacecraft will become one with the planet as it descends deep into the cold gas world.

Cassini’s grand finale has recently started and will hopefully last all summer. Cassini has already flown six times through the perilous, icy debris that we call the rings of Saturn. It’s captured our best views of “hexagon hurricane” that marks Saturn’s north pole, first discovered by Voyager back in 1981. This massive, rotating storm system has an eye 50 times bigger than an average hurricane eye on Earth. Each side of the hexagon is longer than the diameter of Earth!

Will Cassini survive the summer? Looking at its grand finale goal numbers, it seems precarious; but Cassini has been orbiting Saturn for 12 years after a seven-year trip from Earth… The spacecraft is almost 20 years old. It’s been a cosmic workhorse for NASA—what’s another three months? My bet is on Cassini.

Cassini the person was quite prolific, too. Giovanni Domenico Cassini was born almost 400 years ago in Italy. He grew to be an amazing astronomer, discovering four of Saturn’s moons and a gap in its rings. He was also the co-discoverer of Jupiter’s giant red spot. And, to top it off, he figured out the size of the solar system back in 1672!


Eclipses 101

What is a Solar Eclipse?

  • When the Moon blocks the light of the Sun and its shadow covers the Earth.
  • The dark part of the shadow—the umbra—barely reaches Earth and makes a total solar eclipse very rare.
  • It happens during the New Moon phase.

What is a Lunar Eclipse?

  • When the Earth’s shadow covers the Moon.
  • The Moon glows red because sunlight is bent, or refracted, by the Earth’s atmosphere into the spectral colors. However, only the red part of the Sun’s light reaches the Moon.
  • It happens during the Full Moon phase.
  • The next lunar eclipse in Wisconsin is January 31, 2018.

Partial Solar vs. Total Solar—Not the Same!

A Partial Solar Eclipse is:

  • Cool, nice, neat….
  • Not dark, very slight dimming if over 80%.
  • Fairly common, recent Milwaukee partials:  2000, 2001, 2002, 2012, and 2014.

A Total Solar Eclipse is:

  • Breathtaking! Overwhelming! WOW!!!
  • Gets dark! Can see planets, bright stars.
  • Once-in-a-lifetime. If you do not travel to see totality, on average, a total solar eclipse can be seen from the same place only once every 375 years!

Weather: Be Mobile!
Don’t let clouds eclipse your eclipse! Make sure you are mobile—as best as you can. Check weather forecasts for your viewing area. Find a location that is predicted to have clear skies!

Safety First
Even when 99% eclipsed by the Moon, the Sun can still damage your eyes! Make sure you view the eclipse safely. Eclipse shades are available for $2.00 at MPM. They block out all light except the Sun. Sunglasses do not work. Telescopes with special solar filters provide amazing views of the solar eclipse. Check with local Planetarium and astronomy clubs for safe viewing events.

Pinholes are a great way to see the eclipse. Make a tiny small hole and align it so the Sun shines through the hole onto a white sheet or piece of paper. Tree leaves have natural pinholes and can make great “Crescent Suns!” You can even dig around your kitchen for a colander to see the eclipsed Sun.

Timing is Everything!
Double-check your eclipse times for your viewing location. Since weather is always a concern, know your back-up spot times, too. Shown in the graphic are the times for Milwaukee’s partial eclipse. If you are headed to totality, the times will change slightly depending where you’re going. Also, make sure to adjust for timezones.

Heat Stamps
On June 20, the United States Postal Service will issue their first-ever “heat stamp” to commemorate the upcoming August 21 eclipse! The heat from your finger will transform the Moon from black (how it appears during eclipse) to how we see it during a full Moon. Your thumb heat activates the special thermochromic stamp ink to uncover the underlying image. It goes back to black after it cools.

On August 21, the Moon’s shadow will race across 14 states along a narrow path from Oregon to South Carolina; this is the first total solar eclipse to traverse the America’s mainland since 1918. A USA stamp is an excellent way to get people eclipse ready--and teach a little science on the side. Share the heat stamp using #EclipseStamps on social media.


Sailing to the Stars
“Are you kidding me?” is what someone might say in the 1930s if you told them humans will be walking on the Moon in 30 years.

Of course, today, space travel happens all the time. We just don’t go very far, cosmically speaking. There are thousands of satellites in Earth’s orbit. We’ve landed 12 astronauts on the Moon. Robotically, we journeyed to every planet in the Solar System—even our favorite ex-planet, Pluto--but all that is local. Traveling to the stars is a whole new ballgame. One of our fastest ships, NASA’s New Horizons, is traveling at 10 miles per second (think of commuting to work that quickly!). After encountering Pluto in 2015, it would take 78,000 years to arrive at Alpha Centauri, 4.3 light years away.

If I told you we will cut that time of 78,000 years to 20, you might say, “Yeah, right!” Well, there is a group called Breakthrough Initiatives looking to do just that. Their goal is to build a spacecraft that can travel at 20% the speed of light. It’s so small and light, it barely has enough support for the cameras planned—let alone astronauts. The sail ship will harness light energy to make its way across interstellar space.

Famous scientist Stephen Hawking is part of this new group, as is Facebook founder Mark Zuckerberg. Many investors have contributed to their $100 million dollar fundraising goal. The program will be led by Pete Worden, the former director of NASA AMES Research Center. Breakthrough Initiatives was founded in 2015 by Russian entrepreneur and physicist, Yuri Milner, and his wife Julia to advance humanity’s path to the stars.

Sky Sights

Jupiter grabs your attention first thing on any clear June night. See it sparkle brighter than any star high in the south. A waxing gibbous Moon rolls through from June 2-4.

Mars is pretty much done all summer. Its red light is eclipsed by the Sun. Its position lines up too close to our star. On July 27, Mars will be in conjunction with the Sun, straight behind it. We have to wait until September to start spotting it in the morning sky.

Saturn reaches opposition on June 15. (Think of opposition like a full Moon.) Saturn is opposite the Sun and up all night. Look for the full Moon nearby on June 9!


Venus still dominates a morning sky—if you happen to be up awfully early, around 4:30 a.m. -- rising about two hours before the Sun. Look for the Moon shining nearby on June 20-21.

Mercury is out of sight all June.


Star Map

Download the June Star Map.  

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