Planetarium Newsletter - May 2021

Cosmic Curiosities

“Three things cannot be long hidden: the sun, the moon, and the truth.”
- Buddha


Eclipses on the Horizon… On the Horizon

Two eclipses—one lunar, one solar—are on the horizon, literally—in both definitions of the word.

Mark your calendars for May 26 and June 10. Each eclipse favors the early bird—or the extreme night owl. So set your alarm clocks!

May 26, 2021: Super Moon Partial Eclipse - A very early Wednesday morning

may lunar eclipseThis little lunar eclipse might not rank in the upper echelon, but it is still better than the penumbral lunar eclipses we had last year. This time, our moon enters the Earth’s umbra (or darker) shadow and will be more noticeable.

It starts just when the moon is about to set in the west at 4:45 a.m. CDT. Since the moon is barely above the horizon, make sure your eyes have a clear path to the western sky—no trees, hills, or houses to block your view. The moon sets while half eclipsed, 38 minutes later. Even though the sky brightens with the sunrise in the east, the eclipsed moon is still visible if clear. If you get up before the eclipse starts, catch Jupiter and Saturn in the south sky before twilight starts.

People on the west coast of America get to see a total lunar eclipse, but they, too, will have to get up early. If you have any friends or family, let them know about the impending disappearance of the moon in the Earth’s shadow. Eclipse viewers can find their local times at timeanddate.com/eclipse. If you have friends on the other side of the world—say, in Australia or Asia—they will see the lunar eclipse as the moon rises at sunset.

partial lunar eclipse map

The moon glows red during a total lunar eclipse. This is because the sun’s light is dispersed into spectral color when it passes through Earth’s atmosphere. The colors all get refracted (bent) differently because they have various energies. Only the red part of the spectrum is able to reach the moon.

June 10, 2021: Partial Solar Eclipse at Sunrise - A very early Thursday morning

animation of sun risingThe sun has not risen while eclipsed in Milwaukee since December 24, 1973. The moon’s “bite” will hide 31% of the sun at 5:12 a.m. CDT, as it clears the ENE horizon. As our star climbs higher, the moon’s orbit will quickly uncover more and more of the sun. By 5:40 a.m., the eclipse is already over—just 28 minutes long.

This solar eclipse is a great opportunity for photographers to capture a unique sunrise. Like the lunar eclipse, make sure your line of sight is clear to the horizon. Anywhere along Lake Michigan is a great spot.

Your eyes are naturally protected at sunrise or sunset, because you are looking through 40 times more air than when the sun is higher in the sky. So, eclipse glasses will not be needed at the start of this eclipse, but you may need them toward the end.

june solar eclipse map

If clear skies prevail, everyone in Wisconsin can see this eclipse. People in northeast Wisconsin see a slightly longer eclipse. For Green Bay at sunrise, sky watchers can catch a 44% eclipsed sun for 36 minutes. In southwest Wisconsin, the eclipse is shorter. In La Crosse, viewers a 12% eclipsed Sun for just 21 minutes.

Eclipses on the Distant Horizon

On November 19, there is an “almost” total lunar eclipse: 97% of the moon’s light will be in the Earth’s darker umbra shadow. This one will be really tough to see unless you are a night owl—or an extreme early riser.

If clear, bundle up and get away from street lights if you can. A special sky-treat with a total lunar eclipse (or near ones) is to watch more and more stars come out as the bright moon slowly grows darker and turns its orange-red color.

almost total lunar eclipse map

After 2021, mark your calendars for:

May 15-16, 2022: Total Lunar Eclipse
October 14, 2023: Partial Solar Eclipse; 41% max in Milwaukee
April 8, 2024: Partial Solar Eclipse; 90% max in Milwaukee


bright star in skyUnveiling the Veil Nebula

About 7,000 years ago, we humans started to develop cities and civilization. This was mainly due to improved agriculture practices and increased trade. In turn, this allowed people more free time to practice more diverse activities and skills. And more time to stargaze—to ponder and figure out the heavens above.

Around this time, a new star appeared out of nowhere. Anyone who looked up back then would have seen it. Its light was incredibly intense. The cosmic newcomer was five times brighter than Venus and as bright as the crescent moon. It was visible in the daytime. The new star lasted for a month or two, then slowly faded from view.

I imagine astonished stargazers all over the world wondering about this glowing aberration. They certainly shared their thoughts and beliefs with each other. There are no records, though. Writing would not start until another thousand years.

the veil nebulaToday, we know this amazing light was caused by the death of a massive star—a supernova. The original giant star was 20 times more massive than the sun. Its ghostly remains have expanded immensely into what resembles a veil. Today, we call it the Veil Nebula or the Cygnus Loop, because of its location in the constellation of Cygnus the Swan. Numerous parts of the nebula have separate names, as astronomers examine the debris more closely.

Part of this supernova remnant was first seen and recorded by William Herschel in England in 1784, three years after he discovered the planet Uranus. He saw the western edge of the nebula near the star 52 Cygni. Herschel had no idea what produced this flimsy nebula, or that it was an amazing bright star 7,000 years ago. That discovery would not come until 1938 by astronomer Walter Baade when he realized what caused the Crab Nebula, the remains of another supernova in Taurus the Bull.

Today we know the Veil Nebula is enormously vast at 130 light years across. In the night sky, it covers over three times the width of the full moon. The star’s death throes have expanded a stunning distance since it exploded 7,000 years ago.                               

From Earth, the Veil’s distance is about 1,400 light years away. This means the star actually went supernova 8,400 years ago! It took another 1,400 for speed-of-light photons to reach the stargazing eyes of people long ago.

animation of veil nebula

Look very carefully at the image above from the Hubble Space Telescope. Can you see the Veil Nebula expanding? It may seem like a slight motion, but the nebula is moving at more than 200 miles per second! Also, notice the colorful gas and dust clouds of ionized hydrogen, sulfur, and oxygen. This part of the nebula is “only” about two light years of the entire Veil Nebula. 

The reason we can see this vast nebula is because of stellar collisions. Before the star went completely boom, it ejected copious amounts of subatomic particles with its extreme stellar winds. When the giant star detonates as a supernova, the particles from this faster shockwave slams into the slower particles and causes them to glow.

If you would like to see a beautiful veil in the sky with your own eyes, look to the Milky Way galaxy from city lights. Long ago in Estonia, they told an enchanting story of the Milky Way’s white, wispy glow being from a queen’s wedding veil.


Sky Sights  

Click maps to enlarge.

map of may skyAs we lose Orion and his dogs in the west, a great sign of spring in the east is the return of Arcturus and Spica. Look high in the sky to locate the Big Dipper and “star hop” to find these bright and colorful stars!

 

 

 


 

map of may sky map of may sky

The Moon passes in front of Jupiter and Saturn twice this month. The two large gas planets are rising earlier and getting higher each morning about an hour before sunrise. However, you will need to get up earlier! By early August, the two planets rise as the sun sets and will be visible all night long.    

map of may sky map of may sky

Mars, Venus, and Mercury are all visible in the evening sky this month. The red planet is the easiest to observe as it nears the twin stars of Gemini. The two inner planets are much more difficult to see. The maps above are for only 30 minutes after sunset, so it will be fairly bright. Make sure you have a clear path to the western sky. A pair of binoculars will definitely help. The Moon can be used as a guide from May 12-16. Venus and Mercury are very close on May 28, but brilliant Venus will dominate over Mercury, being about 100 times brighter.


May Star Map 

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