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Robert Davidson, shown on the left of the image holding a microphone, seen here conducting a space suit fit check with Astonaut Rusty Schweikart on December 17, 1966.

Online Exhibition: Voices of Apollo

In May 1961, President John F. Kennedy announced a seemingly impossible goal of putting a man on the Moon by the end of the decade. “We choose to go to the Moon,” he declared.

Eight years later the unthinkable would be proven possible. On July 20, 1969, NASA’s Apollo 11 mission would touch down on the surface of the Moon. Nearly 600 million people would watch a televised photo of Commander Neil Armstrong and hear him say, “…that’s one small step for a man, one giant leap for mankind.”

As we celebrate the 50th anniversary of the Apollo 11 lunar landing, we continue to draw inspiration from this monumental event. It took over 400,000 people almost a decade to land two men on the Moon. This “moonshot” was on a global scale never seen before, with an international interest yet to be repeated.

In our latest online exhibition, we’re celebrating all things Apollo—from the collaborative nature of the Apollo program, to memories of the historic event, to continual inspiration for future generations. Hear from a handful of the 400,000 people who made the Moon landing possible, as well as the people who watched this incredible feat in awe from Earth.

Explore “Voices of Apollo” for yourself and check out our other exciting exhibitions, including the historical origins of space exploration and an in-depth look at artist Frederick J. Brown’s Milky Way, on Google Arts and Culture.


Header Image: Robert Davidson, shown on the left of the image holding a microphone, seen here conducting a spacesuit fit check with astronaut Rusty Schweikart on December 17, 1966.

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Robert Davidson, shown on the left of the image holding a microphone, seen here conducting a space suit fit check with Astonaut Rusty Schweikart on December 17, 1966.

Online Exhibition: Voices of Apollo

In May 1961, President John F. Kennedy announced a seemingly impossible goal of putting a man on the Moon by the end of the decade. “We choose to go to the Moon,” he declared.

Eight years later the unthinkable would be proven possible. On July 20, 1969, NASA’s Apollo 11 mission would touch down on the surface of the Moon. Nearly 600 million people would watch a televised photo of Commander Neil Armstrong and hear him say, “…that’s one small step for a man, one giant leap for mankind.”

As we celebrate the 50th anniversary of the Apollo 11 lunar landing, we continue to draw inspiration from this monumental event. It took over 400,000 people almost a decade to land two men on the Moon. This “moonshot” was on a global scale never seen before, with an international interest yet to be repeated.

In our latest online exhibition, we’re celebrating all things Apollo—from the collaborative nature of the Apollo program, to memories of the historic event, to continual inspiration for future generations. Hear from a handful of the 400,000 people who made the Moon landing possible, as well as the people who watched this incredible feat in awe from Earth.

Explore “Voices of Apollo” for yourself and check out our other exciting exhibitions, including the historical origins of space exploration and an in-depth look at artist Frederick J. Brown’s Milky Way, on Google Arts and Culture.


Header Image: Robert Davidson, shown on the left of the image holding a microphone, seen here conducting a spacesuit fit check with astronaut Rusty Schweikart on December 17, 1966.

Michelle Nichols helping young skywatchers observe the sky at a 'Scopes in the City event.

Building Community Under the Stars

Michelle Nichols


In September 2016, we—the Adler’s ’Scopes in the City team—brought a telescope to the Wrightwood-Ashburn library branch on Chicago’s southwest side and set it up in front of the library. This branch has a beautifully clear view of the sky with no tall buildings in the way. A teen involved in other library programs came up and started to hang out with me. I showed her how to use the telescope, and she immediately began explaining how the telescope works to other passers-by.

I stepped back and let her lead the effort. She was incredibly engaging, and quite a few people stopped to look through the telescope, chat, and ask questions, many hanging out with us for 30 minutes or more. One little girl looked through the telescope more than a dozen times. A group of ladies from the library’s knitting club came outside after finishing their meeting. We invited them to look through the telescope, and the exclamations of delight were amazing. In return, the ladies offered us cupcakes. Our telescope was the center of an impromptu little community for an hour.

When people find out I have been working at the Adler Planetarium for almost 24 years, they often ask me, “What is the best part of your job?” The answers are almost endless, but the one thing I keep coming back to is this:

The excitement, glee, wonder, or shock on a person’s face when she or he looks through a telescope for the first time is inspiring. Seeing spots on the Sun (safely, of course!), moons of Jupiter, rings of Saturn, craters on the Moon with your own eyes—seeing these dots and places as real worlds, seeing them as they look in pictures in a book or magazine—these are the experiences that, for many people, instantly turn astronomy from an esoteric subject into a Universe of real places.

In 2014, the Adler Planetarium debuted ’Scopes in the City to bring telescope observing to people where they are and get eyeballs to the eyepiece. It was obvious from the beginning that ’Scopes was going to be impactful, and it was also obvious that we were going to need some help to reach people. In 2015, we began searching for a partner, and the Chicago Public Library seemed like a natural fit. Eighty library branches are located all over Chicago, and libraries provide an impressive array of services to Chicago residents.

When we began talking with the Teen Programs staff at the Harold Washington Library about what we could do together, facilitating ’Scopes in the City programs at library branches seemed to all of us like a slam-dunk. Starting with two grants from the Hive Chicago Learning Network, we surveyed all of the library branches in person to ascertain how much of the sky could be seen from each location, compiled check-out kits of astronomy and optics materials for librarians to use in their programs, purchased several telescopes that would be housed at five branches, and taught library staff how to use those telescopes. We also taught a number of teens at YouMedia technology centers how to use the telescopes.

Our partnership has continued. This past summer, four of our teen interns worked with Adler staff to provide ’Scopes in the City observing experiences at 10 library branches. In part thanks to the Chicago Public Library Teen Services Department, ’Scopes in the City has grown from four pilot events reaching 600 people in 2014 to almost 40 events reaching more than 2,000 people in 2018.

Pointing out stars, planets, the Moon, the Sun, showing nearby worlds in our Universe, cultivating temporary telescope communities, and working closely with a partner such as the Chicago Public Library is critical to the success of ’Scopes, and the responses from our partners and the community inspire me every day.

That night in 2016, after the event at the Wrightwood-Ashburn library wrapped and everyone else had left, the branch manager asked if I could show her where the Big Dipper was in the sky. I told her to turn around and face north. The Dipper was resting in the sky just above the roof of the library. She saw it, screamed, and gave me a big hug. She said, “I have wanted someone to show me where the Big Dipper was for my whole life. Thank you!”

The Moon surface as seen via the Adler's Doane Observatory in April 2017.

Adler Skywatch: July 2019

Karen Donnelly

Header Image: Moon surface taken by the Adler’s Doane Observatory on April 7, 2017.


The nation celebrates the 50th anniversary of NASA’s Apollo 11 mission this month, July 2019. It was 50 years ago on July 20 when humans first set foot on Earth’s natural satellite.

It’s a big month for the Moon astronomically as well. This month, when we commemorate humankind’s first steps on the lunar surface, there are two New Moons—on July 2nd and on the 31st. (Note: New Moons are not ever visible.) The evening of the Full Moon, the 16th, is 50 years to the day since the launching of Apollo 11.

The Moon also plays another special role on the 2nd (though in the daytime sky and in a different hemisphere) when it passes in front of the Sun to cause a total solar eclipse. Unfortunately, this eclipse won’t be visible at all in Chicago, nor in most of the Northern Hemisphere. The path of totality, where the Moon will completely cover the Sun, traces a thin line across the southern Pacific Ocean and through the nations of Chile and Argentina. The area where the Moon only partially covers the Sun will stretch across most of South America and small parts of southern Central America.

During evening twilight in the Chicago area this month, look low in the southeast sky to spot the planet Jupiter. It’s the brightest planet in the night sky this month since the planet Venus rises too close to sunrise to be readily visible. Jupiter is also brighter than any star in the July sky, so it’s easy to spot. This month it’s five to eight degrees to the left of the reddish star Antares, in the constellation Scorpius. The evening of the 13th, Jupiter appears near a waxing gibbous Moon. Jupiter moves low across the southern sky this month, setting in the southwest about 3:30 am CDT at the start of the month and about 1:30 am CDT by month’s end.

The planet Saturn appears about 30 degrees east of Jupiter. At the start of the month, it rises in the east-southeast as evening twilight ends—but by the end of the month, it’s already well above the horizon before sunset. Saturn outshines the nearby stars low in the southern sky this month—only Jupiter shines brighter. The night of the 15th and in particular the early morning darkness of the 16th, Saturn appears less than a degree away from the nearly Full Moon. It’s low in the west-southwest just before the start of morning twilight.

The planets Mercury, Venus, and Mars all appear very close to the Sun this month and thus will be difficult if not impossible to see.

Aphelion, the point in Earth’s orbit when the Sun is at its furthest for the year, falls on July 4th at 6:10 pm CDT. How far away is the Sun from Earth at aphelion? It’s roughly 94-million miles distant. By comparison, at perihelion—when the Earth is closest to the Sun—we are about 91-million miles away. Perihelion occurred earlier this year, on January 2nd.

The annual Southern Delta Aquarid meteor shower peaks in late July. This year the peak is expected around the 28th. The southern hemisphere is actually the best place to see this meteor shower; so from our northern-hemisphere location, only a handful of meteors might be seen from a dark sky location, far from city lights. The best times to try spotting these quick streaks of light in the night sky are the hours after midnight and before morning twilight. The shower’s peak falls only a few days before New Moon, so the night sky will indeed be dark—as long as you’re far away from artificial light, which washes-out all but the brightest meteors. From light polluted urban or suburban skies, this shower may not be visible at all.

New Moon: July 2nd and 31st
First Quarter Moon: July 9th
Full Moon: July 16th
Last Quarter Moon: July 24th

Please note: these descriptions are for the Chicago area, using Central time.

Tunguska: Unraveling the Mystery

Setting: Tuesday, June 30, 1908, around 7:15 am. A remote forest near the Podkamennaya Tunguska River in Siberia.

A large fireball streaks through the sky followed by an intense wave of heat felt up to 40 miles away. A loud explosion. The ground shakes. Silence.

If the playwrights of today were to write a theatrical piece about the mysterious event that took place 111 years ago in remote Russia, its introduction would look something like the above. A rather bold, dramatic scene set for something that would become a century-long debate. The event near the Podkamennaya Tunguska River was unexplainable by locals—or rather the multiple accounts of the incident didn’t always add up. Some people saw an explosion. Others only felt tremors or heard an explosion. Indigenous peoples to the area (the Evenkis and Yakuts) even believed a god had sent the fireball to destroy the world.

Following the occurrence, Russian newspapers would report the event as a possible meteorite impact. Over the decades, others would hypothesize a volcanic eruption of some kind. In the 1970s, American physicists would propose the phenomena as a small black hole colliding with Earth. Whatever it was, as many as three casualties were reported in the area. And it’s thought that there was up to 30 individuals in the blast zone. It is unclear how many of them may have survived.

Due to the remoteness of the region, as well as the political situation of the time (the Russian Revolution and the outbreak of WWI), scientific investigation at the potential site of impact was delayed for nearly 20 years, leaving a lot of room for speculation.

Leonid Alekseyevich Kulik of the Russian Meteorological Institute, circa 1929.

Leonid Alekseyevich Kulik of the Russian Meteorological Institute would eventually become interested in the area. In 1927, he would send an expedition team to the site with the hope of finding meteorite fragments and materials. They would discover that the area impacted by the event would cover approximately 800 square miles. One of the most peculiar things found by Kulik and his team was at “ground zero” where they expected to find a large impact crater. Instead of a massive hole, the team would discover a five square mile zone with scorched trees devoid of branches, standing upright in a pattern pointing away from the center.

In the end, Kulik’s team would come up short on their search for meteoritic fragments.

Scorched trees found at ground zero of the Tunguska Event site.

Ultimately, scientists and historians have come to conclude that, despite the lack of meteoritic material found in the area, the probable cause of the Tunguska Event (as it has come to be known) was indeed a meteorite impact. Likely from an asteroid that was originally 40-80 meters in size.

But how do we know? Many of the anecdotal accounts of the incident, as well as the supporting evidence from the butterfly-shaped blast pattern at the impact site, help support this conclusion.

“In the 1960s, the Soviets experimented recreating the blast site by sliding explosives down a wire into mini model forests,” explains Adler astronomer Mark Hammergren.

The experiments suggested that the hypothesized meteorite approached the Tunguska site at an angle of roughly 30 degrees from the ground and 115 degrees from north, and likely exploded in mid air. This would also help explain why a large impact crater was never discovered at the site.

Small meteors enter and burn up in the Earth’s atmosphere every single day, never coming near to having impact with the ground. Scenarios like the Tunguska Event are much rarer. It is estimated that they occur every 300 to 1,000 years.

Today, scientists have found and mapped the course of approximately 97% of asteroids bigger than 1 km in our Solar System. These are the asteroids that could wipe out entire cities. They’ve also cataloged the course of virtually all asteroids that are bigger than 5 km in diameter (in other words, asteroids that are sizable enough to destroy civilization as we know it). The good news is that none of these existence-threatening asteroids are on a collision course with Earth!

As of 2018, over 18,000 known near-Earth orbit asteroids have been discovered and the discovery rate averages about 40 per week. Scientists are already planning for one particular asteroid’s flyby a whole decade away. This animation shows the distance between the Apophis asteroid and Earth at the time of the asteroid’s closest approach. The blue dots are the many man-made satellites that orbit our planet, and the pink represents the International Space Station. Credit: NASA/JPL-Caltech

We don’t know when the next Tunguska-like event will be. However, it’s likely that with advances in today’s technology, and the number of astronomical surveys happening across the globe, whenever that day comes, we will have enough warning to be able to evacuate any threatened areas that are populated with people. And humanity will continue on, business as usual.

Header Photo: View of the Tunguska Event impact site as seen on Google Earth.

The Big Dipper in the Night Sky

Discover: The Big Dipper

It’s night and you’re looking up into the night sky. What’s the first constellation you see? If you thought to yourself “the Big Dipper,” you’re not alone! In Western culture, it’s often one of the first things we learn to recognize in the night sky as children.

For many people in the United States, this recognizable grouping of stars represents a large spoon. Three stars make up the “handle” and four stars make up the “bowl.” But did you know that two of the stars in the bowl, known as Merak and Dubhe, can actually help you find Polaris, or the North Star?

Use the Big Dipper to find Polaris—the North Star. Note that Polaris is actually the first star in the Little Dipper’s “handle.”
Use the Big Dipper to find Polaris, the North Star, which will also lead you to the Little Dipper!

But that’s not all! Get ready to impress your friends at parties because the Big Dipper can also help you find the star Arcturus during the spring and summer months. And if you’re lucky enough to spot Arcturus, congratulations! That means you’ve also spotted Boötes the Herdsman, as Arcturus is the brightest star in that constellation.

The Big Dipper’s “handle” points to the star Arcturus and you can use the method above to find Arcturus in the spring and summer months in Chicago when it’s above the horizon.

The Big Dipper itself is actually a part of Ursa Major, a constellation in the northern sky that borrows its name from antiquity. In Latin, Ursa Major means “the greater bear.” It is one of the 48 constellations cataloged by the Greco-Roman astronomer Ptolemy in the second century and one of the 88 modern constellations recognized by the International Astronomical Union (IAU).

Card from Urania's mirror: or, A view of the heavens (1825), Adler Library
A traditional depiction of the Great Bear from Urania’s Mirror, a set of constellation cards originally published in 1825. The cards are perforated so that, when held against a source of light, they recreate the appearance of shining stars in the night sky.
Card from Urania’s mirror: or, A view of the heavens (1825), Adler Library

The Big Dipper can be found in myths, folklore, and depictions all over the globe

In Roman mythology, the Big Dipper is associated with the beautiful nymph Callisto who gave birth to the son of Jupiter (Zeus in Greek mythology). Juno (Greek Hera), the wife of Jupiter, turned Callisto into a bear out of jealousy as to punish Callisto and take away her beauty. In one version of the story, Callisto would come across her child all grown up many years later. Just as her son was about to slay his own mother, Jupiter would appear and avert the situation by placing them both amongst the stars.

In Arabian lore, the Big Dipper is associated with funerals. The bowl represents a coffin and the three stars in the handle are mourners following behind it.

Stories in some Native American groups saw the stars in the bowl of the Big Dipper as a bear, while the stars in the handle are hunters chasing it. Alternatively, the handle is interpreted as the tail of the bear and the bowl is part of the hindquarters.

 Plate from Julius Schiller, Coelum stellatum Christianum (1627), Adler Library
Plate from Julius Schiller, Coelum stellatum Christianum (1627), Adler Library

The pattern of stars that forms the Great Bear is depicted as St. Peter’s Boat in this map from Julius Schiller’s Coelum stellatum Christianum (1627), where he tried to Christianize the constellations that Europeans inherited from Mesopotamia and Ancient Greece, and which had also been adopted by Islamic astronomers.

If you look carefully, you will be able to see the Big Dipper on the upper right side of the boat, with the Pointers just next to the mast (also in this case, the positions of the stars are reversed, as if seen on the surface of a celestial globe). Schiller’s constellations failed to gain any footing, but besides their impressive artistry, they are also a reminder that the night sky is open to everyone’s imagination!

Searching for the Big Dipper

So, how do you see the Big Dipper in a place like Chicago? Easy! First, refer to this phrase: spring up and fall down. Similar to the way “spring forward, fall back” helps us remember which way to turn our clocks during daylight savings time, “spring up and fall down” tells us where to find the Big Dipper in the sky each night. As you might guess, during the spring months, you’ll catch it high in the sky. And during the fall, you’ll find it low, close to the horizon. (Note that even when the Big Dipper is close to the horizon it will never fully go beyond, so you’ll be able to find it at any time of night!)

Next time you step outside to #LookUp at the Big Dipper, think about its fascinating and culturally rich significance in our night sky. Then remember that people all over the world are also looking up at this same grouping of stars and telling their own stories about what it means to them.


Head Image Photo credit: slworking2 on VisualHunt.com / CC BY-NC-SA

An artist's illustration of a brown dwarf. Image Credit: NASA

AstroFan: It’s a star! It’s a planet! No—it’s a brown dwarf?!

Bianca Anderson

Image Credit: NASA/JPL-Caltech

Our Universe is filled with strange objects that even scientists have trouble classifying. Read on to learn about brown dwarfs, the celestial objects that are kind of like a star and kind of like a planet but are actually neither.


A wise man once said, “Only a Sith deals in absolutes”.

That wise man was a jedi-master named Obi-Wan Kenobi, and he said those words during the climactic battle on planet Mustafar in (arguably) one of the greatest episodes of Star WarsRevenge of the Sith.

In the case of brown dwarfs, most astronomers would agree with master Obi-Wan. For today’s topic, it is most salient that we stray far, far away from speaking in absolutes.

You see, brown dwarfs are very wonky in that they are neither a star nor a planet—they’re sort of something else entirely.

The life of a brown dwarf starts off similar to a star; both form from a collapsing cloud of gas and dust. The difference here is that once brown dwarfs form, they lack the mass that is needed to support nuclear fusion.

Nuclear fusion is when low mass atomic nuclei are built up into higher mass atomic nuclei in a star’s core, releasing energy and fueling the star in the process.

Since brown dwarfs don’t have nuclear fusion they behave differently than a star and are essentially massive objects composed of gas and dust with no fuel to burn. Brown dwarfs are less massive than the Sun but much more massive than gas giants (i.e. 13 to 90 times more massive than Jupiter).

Image Credit: Carnegie Institution for Science

When a brown dwarf first forms, it starts out being pretty hot due to the physical forces that made it, but without nuclear fusion, brown dwarfs inevitably cool as they age. Higher mass brown dwarfs cool a lot more slowly and have a higher luminosity for a longer period of time than lower mass brown dwarfs. Most brown dwarfs glow in the red and infrared spectrum of light.

A fun fact about brown dwarfs is that shortly after they were first predicted in the 1960s, scientists thought that their existence could explain the mysterious case of dark matter. (For those who don’t know, dark matter is a material that is unobservable to scientists and is believed to make up 80% of the mass in the Universe.) It later turned out that brown dwarfs were nowhere near numerous enough to be an important component of dark matter!

Although the existence of brown dwarfs didn’t explain the mysteries of dark matter, it has been suggested by some that brown dwarfs could offer another way for life to thrive in our Universe.

Recently, researchers at Harvard University proposed that the upper-atmosphere of some brown dwarfs may have habitable conditions for life. We’re talking a microbial oasis of water vapor, warm temperatures, and nutrients. Think about thatlife thriving in the clouds of these non-planets!

Speaking of atmospheres, when it comes to brown dwarfs, things get… interesting. Unlike the atmospheres of stars, brown dwarfs have atmospheric winds that fall into regular belts and zones.

Due to their higher masses, it has been hypothesized that the storms that occur on brown dwarfs are larger and more powerful than the ones typically seen on the gas giants in our Solar System.

An artist’s rendition of what a storm on a brown dwarf could look like.
Image Credit: NASA/Cal-tech

As you can see, brown dwarfs fall into a league of their own. Their very existence has helped astronomers begin to bridge the gap between gas giants and stars.

Brown dwarfs prove that sometimes it is very difficult to group celestial objects into neatly delineated categories. They prove that sometimes the natural world creates objects that have such unique characteristics that they completely change the way astronomical objects are categorized.

So, if you’re ever at a dinner party and hear someone say “ A brown dwarf IS a star” or “A brown dwarf IS a planet,” remember the wise words of Obi-Wan Kenobi…

Stay tuned for more awesome space facts on the next AstroFan.

Thank you for reading!

—Bianca, a.k.a. AstroFan

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