The Adler 'Scope

Featured Article

The Winter Solstice will occur on December 21st, 2019 at 10:19pm

Adler Skywatch: December 2019

Header Image: Graphic representation of the Winter Solstice which will occur on December 21st, 2019 at 10:19pm.

The brightest planet, Venus, begins a run of many weeks’ worth of spectacular viewing in the evening skies this month, December 2019.

Venus starts off the month very low in the southwest after sunset, setting only about 90 minutes after the Sun. However, it moves higher in the evening sky each passing night. By the end of the month it sets nearly three hours after sunset. It also gets a little brighter every evening this month; and will continue to do so through the month of April 2020. The night of the 28th, look for Venus near the top of a very slim waxing crescent Moon.

Not far from Venus this month is the dimmer planet Saturn. Through the 10th Saturn appears less than ten degrees above Venus, low in the southwest sky. After that date the two planets appear side-by-side for a few nights. By the 14th, Saturn is below Venus in the sky; and by the 19th, Saturn is so close to the southwest horizon it becomes difficult to view.

Early risers can try spotting the planet Mars low in the southeast sky during morning twilight. It rises about three hours before the Sun this month. It doesn’t get much brighter than 1.6 magnitude this month, and soon fades as the early-morning sky brightens.  

The planets Jupiter and Mercury appear so close to the Sun this month that they are difficult if not impossible to view.

The annual Geminids meteor shower occurs this month, peaking the night of the 13th and into the early morning darkness of the 14th. The bright waning gibbous Moon on those dates will wash out fainter meteors. However, Geminids tend to be bright – plus, they tend to be plentiful, with up to 100 meteors per hour under very dark, very clear skies. Expect to see far fewer if you’re viewing near city lights. No special equipment is needed to view meteors — just find a clear, dark, safe place, face east, and look up.

The winter solstice occurs at 10:19 p.m. Central time on the 21st.  For the northern hemisphere, this is the date with the shortest period of daylight and the longest period of nighttime; the Sun is at its lowest in the sky for the year. Late that same night and past midnight the following day, see if you can spot any meteors during the annual Ursids meteor shower, which peaks at this time. The Ursids have an expected maximum of only five to ten meteors per hour; but this year they occur when the Moon is waning and low in the sky, which will help aid visibility. Remember: the darker the sky, the better the viewing.

Finally, if you’re traveling overseas for the holidays, an annular solar eclipse takes place the 26th. This type of eclipse occurs as the Moon is near the farthest point in its orbit around the Earth and, thus, it does not appear large enough from Earth to completely cover the Sun, as during a total solar eclipse. The word “annular” is from the Latin word “annulus,” which means “ring.” In this case, the ring refers to the ring of Sun that shows around the Moon during the peak of the eclipse. Unfortunately, Europe, North and South America, and Africa will miss out on seeing this one. The annular eclipse will be visible in parts of Saudi Arabia, Qatar, United Arab Emirates, Oman, India, Sri Lanka, Malaysia, Indonesia, Singapore, Northern Mariana Islands, and Guam, and a partial solar eclipse will be visible from northeast Africa and the Middle East to much of eastern and southern Asia. Refer to mreclipse.com for a specific visibility map for this eclipse.  And, wherever you are, remember to never look directly at the Sun without proper safe-solar filters. There is absolutely no time during an annular solar eclipse when the Sun and Moon combination is safe to view with unaided eyes.

  • First Quarter Moon: December 4th
  • Full Moon: December 11th  
  • Last Quarter Moon: December 18th
  • New Moon: December 25th

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

Read More

Latest Articles

See You Another Time (Or Somewhere Else)!

Pedro Raposo

Header Image: Woman looking at a few of the astronomical objects from our collection located in the Adler Planetarium’s new exhibit, Chicago’s Night Sky.

One of the most exciting—and at the same time most difficult — parts of an exhibition project is to decide which collections items will be put on display. 

The Adler team has increasingly favored a careful and restricted choice of objects that strengthen the exhibition narrative and highlight its core messages, rather than overwhelming our guests with an abundance of things that will likely distract them. 

There are also several other types of considerations at play, which include the condition and conservation needs of each object; the safety of both staff and visitors (especially important when we deal with large and complex artifacts); the amount of resources that displaying a particular item might require; and ultimately, how each object choice will help advance the goals of the exhibition, and, more broadly, the Adler’s mission and values.

Here we present some examples of items that were initially considered for Chicago’s Night Sky, but that did not make it in the end for varied reasons. Don’t worry though; there will be many other opportunities for you to see them at the Adler. And there are other ways to learn about the stories of these and other items that were left out of Chicago’s Night Sky—which, needless to say, just ended up with a more refined and compelling object list!

OBJECT 1: STAR CHART BY MASAKI MASAFUSA

The primary goal of the exhibition is to invite the Chicagoland communities to look up, but we also want to show that engagement with the night sky is a fundamental human experience that takes place across different cultures. This large Japanese star chart helps make that point, but it would require a special frame or display case, and we cannot leave it exposed to light for too long. We will use an intermediate solution: there will be a good reproduction on display, clearly identified as such, an approach that we will also apply to other works posing similar concerns. Additionally, we will have on display a beautiful 19th-century Japanese astronomy book that has long been in storage, and which pages we can easily turn every few months.

Star chart by Masaki Masafusa, Japan, 1784, Adler collections.

OBJECT 2: SATALLITE TRACKING TELESCOPE

If you are going to look up, you will need a telescope, right? Well, not necessarily. We wanted Chicago’s Night Sky to emphasize that, and you will see on display several tools designed to help stargazers find their way through the stars with the unaided eye. The instrument shown here was used by young stargazers at the Adler in the late 1950s and in the 1960s to track down satellites. It was left out as it refers to a more specialized and complex type of observation.

Satellite tracking telescope, Edmund Scientific Corporation, United States, c. 1960, Adler collections.

OBJECT 3: STAR CHART FROM JOHN HILL

The night sky has always ignited the imagination of stargazers—sometimes a bit too much. The 18th-century British writer John Hill decided to expand on the role of animal constellations in the Western tradition by placing critters such as a leech (Hirudo, shown below) and an earthworm on the heavens.

Although Mr. Hill’s constellations never took off (we wonder why…) they testify to both the creativity and the humor of stargazers. However, we wanted to give more room in the exhibition to sky knowledge from non-Western cultures, thus the book presenting Hill’s constellations was left out. However, you might still come across them in a special Zooniverse interactive that will also be part of Chicago’s Night Sky.

Detail of star chart from John Hill, A new astronomical dictionary (1768), Adler Library. 
An artist’s illustration of Kepler-452b.

Exoplanets: Sci-Fi vs. Fact

Grace Wolf-Chase, Ph.D.

Header Image: An artist’s illustration of Kepler-452b. Image Credit: NASA Ames/JPL-Caltech/T. Pyle


I was an undergraduate physics major at Cornell University, with my eye on a career in astronomy, when I saw the original Star Wars movie following its release in 1977.

A GIF of the opening crawl for Star Wars: A New Hope.

A rather famous astronomer and science popularizer named Carl Sagan, was a professor at Cornell at the time. Sagan was known for stimulating the public’s imagination concerning the possibility of life on distant planets, but in 1977, the only planets we knew for sure existed were the worlds that orbit our Sun.

It wasn’t until the mid-1990s, shortly before Sagan’s untimely passing, that the first planet was discovered orbiting a star similar to our Sun. During subsequent years, the discoveries started coming in at an exponential pace. Currently, there are more than 4,000 confirmed exoplanets! 

Sci-Fi has often foreshadowed the diversity of real worlds, and Star Wars is no exception. As we anticipate the opening of Star Wars: The Rise of Skywalker, it’s fun to compare the imaginative worlds conceived for the Star Wars universe with existing worlds in our own Galaxy.

Let’s start with the closest potentially-habitable exoplanet, Proxima Centauri b, which happens to orbit the star nearest to our Sun—a dim red dwarf that is a “mere” 4.2 light-years away. 

This artist's impression shows a view of the surface of the planet Proxima b.
This artist’s impression shows a view of the surface of the planet Proxima b. Image Credit: ESO/M. Kornmesser

Star Wars depicts forest worlds like Endor in Return of the Jedi, or Takodana in The Force Awakens, as green like our Earth, but astrobiologists speculate that plant life on habitable worlds orbiting stars that emit mostly infrared light, like Proxima Centauri, might be red, black, or even rainbow-colored. 

A GIF from an Endor scene in Star Wars: Return of the Jedi.

Such worlds should be “tidally locked,” with the same side of the planet always facing its star. Just as seaweed changes color from green to dark brown at greater depths in the ocean, the color of any photosynthetic life on such a planet would depend upon its location.

Another notable exoplanet is Kepler-16b. At a distance of 200 light-years, Kepler-16b orbits two stars and was affectionately dubbed “Tatooine,”  after Luke Skywalker’s home planet with its own two suns.

GIF of Luke Skywalker viewing the famous "binary sunset" in Star Wars: A New Hope.

Unlike Tatooine, Kepler-16b is Saturn-sized and very cold, but gas giant Kepler-453b orbits at a potentially habitable distance from its own two suns. Might this world have a habitable moon like Endor?! 


This artist's concept illustrates Kepler-16b.
This artist’s concept illustrates Kepler-16b. Image Credit:  NASA/JPL-Caltech/T. Pyle

Some exoplanets are “Super-Earths”—worlds larger than Earth but smaller than gas giants, that may support large oceans—reminiscent of Kamino in Attack of the Clones or Scarif, in Rogue One

At a distance of 600 light-years, Kepler-22b is 2.4 times the size of Earth, and may be one such world. Other exoplanets are very hot, like Kepler-10b or Kepler-78b, which are molten Earth-sized worlds that bring to mind Mustafar in Revenge of the Sith

A GIF of Anakin Skywalker and Obi-Wan Kenobi dueling on the planet Mustafar in Star Wars: Revenge of the Sith.


Still, other worlds are extremely cold—like OGLW 2005-BLG-390L, one of the most distant known exoplanets. 

Artist’s rendition of OGLW 2005-BLG-390L.
Artist’s rendition of OGLW 2005-BLG-390L. Image Credit: NASA

Located near the center of the Milky Way at a distance of 21,530 light-years, this world is an icy Super-Earth that’s been unofficially nicknamed “Hoth,” after the frigid planet depicted in The Empire Strikes Back

A GIF of Chewbacca in a wintry blizzard on the planet Hoth, in Star Wars: The Empire Strikes Back.

What about really old exoplanets that might have developed into high-tech worlds like Coruscant, the seat of government for the Galactic Republic and the Empire? 

A Super-Earth known as Kepler-452b orbits a star 1,402 light-years away that’s about 1.5 billion years older than the Sun. The PHL places Kepler-452b at the top of their “optimistic sample” of potentially-habitable exoplanets, a bit less likely to be habitable than the 21 exoplanets that make it to their “conservative” list (which includes the “nearby” Proxima Centauri b.) 

An artist’s illustration of Kepler-452b.
An artist’s illustration of Kepler-452b. Image Credit: NASA Ames/JPL-Caltech/T. Pyle

There’s also some evidence of exoplanet destruction, albeit not by the Death Star that caused Alderaan’s demise in A New Hope

In some cases, real stars may consume planets that orbit too close.

No worries about that happening to Earth—although the Sun will make conditions toasty on Earth in the next billion years or so.

Perhaps we, like the civilizations depicted in Star Wars, will have traveled to distant worlds by then. 

Finally, it’s important to note that we’ve not (yet) discovered evidence of extraterrestrial life, and many of the known exoplanets would be hostile to life as we know it. 

However, it’s beginning to look like planet-sized worlds may outnumber stars in the Universe, and that leaves many of us thinking that it’s only a matter of time… 

Until then, may the force be with you!

A GIF of Han Solo giving his signature salute.

The Winter Solstice will occur on December 21st, 2019 at 10:19pm

Adler Skywatch: December 2019

Karen Donnelly

Header Image: Graphic representation of the Winter Solstice which will occur on December 21st, 2019 at 10:19pm.

The brightest planet, Venus, begins a run of many weeks’ worth of spectacular viewing in the evening skies this month, December 2019.

Venus starts off the month very low in the southwest after sunset, setting only about 90 minutes after the Sun. However, it moves higher in the evening sky each passing night. By the end of the month it sets nearly three hours after sunset. It also gets a little brighter every evening this month; and will continue to do so through the month of April 2020. The night of the 28th, look for Venus near the top of a very slim waxing crescent Moon.

Not far from Venus this month is the dimmer planet Saturn. Through the 10th Saturn appears less than ten degrees above Venus, low in the southwest sky. After that date the two planets appear side-by-side for a few nights. By the 14th, Saturn is below Venus in the sky; and by the 19th, Saturn is so close to the southwest horizon it becomes difficult to view.

Early risers can try spotting the planet Mars low in the southeast sky during morning twilight. It rises about three hours before the Sun this month. It doesn’t get much brighter than 1.6 magnitude this month, and soon fades as the early-morning sky brightens.  

The planets Jupiter and Mercury appear so close to the Sun this month that they are difficult if not impossible to view.

The annual Geminids meteor shower occurs this month, peaking the night of the 13th and into the early morning darkness of the 14th. The bright waning gibbous Moon on those dates will wash out fainter meteors. However, Geminids tend to be bright – plus, they tend to be plentiful, with up to 100 meteors per hour under very dark, very clear skies. Expect to see far fewer if you’re viewing near city lights. No special equipment is needed to view meteors — just find a clear, dark, safe place, face east, and look up.

The winter solstice occurs at 10:19 p.m. Central time on the 21st.  For the northern hemisphere, this is the date with the shortest period of daylight and the longest period of nighttime; the Sun is at its lowest in the sky for the year. Late that same night and past midnight the following day, see if you can spot any meteors during the annual Ursids meteor shower, which peaks at this time. The Ursids have an expected maximum of only five to ten meteors per hour; but this year they occur when the Moon is waning and low in the sky, which will help aid visibility. Remember: the darker the sky, the better the viewing.

Finally, if you’re traveling overseas for the holidays, an annular solar eclipse takes place the 26th. This type of eclipse occurs as the Moon is near the farthest point in its orbit around the Earth and, thus, it does not appear large enough from Earth to completely cover the Sun, as during a total solar eclipse. The word “annular” is from the Latin word “annulus,” which means “ring.” In this case, the ring refers to the ring of Sun that shows around the Moon during the peak of the eclipse. Unfortunately, Europe, North and South America, and Africa will miss out on seeing this one. The annular eclipse will be visible in parts of Saudi Arabia, Qatar, United Arab Emirates, Oman, India, Sri Lanka, Malaysia, Indonesia, Singapore, Northern Mariana Islands, and Guam, and a partial solar eclipse will be visible from northeast Africa and the Middle East to much of eastern and southern Asia. Refer to mreclipse.com for a specific visibility map for this eclipse.  And, wherever you are, remember to never look directly at the Sun without proper safe-solar filters. There is absolutely no time during an annular solar eclipse when the Sun and Moon combination is safe to view with unaided eyes.

  • First Quarter Moon: December 4th
  • Full Moon: December 11th  
  • Last Quarter Moon: December 18th
  • New Moon: December 25th

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

This image depicts the thick ring of dust that can obscure the energetic processes that occur near a supermassive black hole of an active galactic nuclei.

AstroFan: A Feast Fit For A Black Hole

Bianca Anderson

Header Image: An artist’s illustration of a thick ring of dust near the supermassive black hole of an active galactic nuclei. Image Credit: NASA / SOFIA / Lynette Cook


Ah yes, it is the day after Thanksgiving, and I bet you’re currently dealing with the inevitable ‘post-feast malaise’. 

What if I told you that at this very moment in time, there were countless black holes experiencing a Thanksgiving-worthy “feast” of their own?!

Today, we’re going to be exploring the strange (yet incredibly common) world of supermassive black holes and active galaxies.

Bring out your stretchiest sweatpants—it’s time for us to partake in a galactic feast!

Supermassive Black Holes 101

Before we dive into active galaxies, we’re going to have to do a quick crash course on black holes—more specifically—supermassive black holes.

As you may know, black holes are objects that have such a strong gravitational pull that nothing (not even light) can escape them. 

There are two main known types of black holes, stellar black holes and supermassive black holes. 

Stellar black holes are black holes that form as a result of a massive star (much larger than our Sun) collapsing in on itself.

Stellar black holes can be as massive as 30,000,000 times our Earth! Sounds like an insane amount of mass, right? 

But wait! Things get even crazier when talking about supermassive black holes.

A mass chart for dead stars and black holes.
A mass chart for dead stars and black holes. Image Credit: NASA/JPL-Caltech

Supermassive black holes can be up to 12 quadrillion times as massive as our Earth! Unlike stellar black holes, scientists aren’t exactly certain how supermassive black holes are formed or how they become so unbelievably massive.

But there is one thing that scientists are almost certain of: at the center of every galaxy lies a supermassive black hole. 

That’s right folks—even our very own Milky Way has one at its center!

So, what happens when large sums of gas, stars, and other celestial debris find themselves within close orbit of one of these monstrous beasts? The answer is…active galaxies!

What Are Active Galaxies?

As mentioned above, it is believed that nearly all of the galaxies in the observable Universe have a supermassive black hole at their center. The difference between an active galaxy and a non-active galaxy, is that an active galaxy’s supermassive black hole has fuel to burn—or shall we say fuel to feast on!

The anatomy of an active galaxy can be broken down into 3 main parts: a supermassive black hole, an accretion disk, and the jets.

The swirling mass of dust and gas that orbits the supermassive black hole is called an accretion disk. 

The region of the accretion disk that is closer to the black hole moves at a much faster rate than the outer region of the accretion disk. As a result, the material within the disk rubs together at speeds a fraction of the speed of light, causing the accretion disk to heat up to extreme temperatures. As the matter spirals and falls towards the black hole, the immense energy that is produced gets emitted as light. 

Sometimes, these accretion disks produce magnificent jets of charged particles that move away from the poles of the black hole at super high speeds—this is also known as a quasar. 

An artist's rendition of a quasar at the center of an active galaxy.
Artist’s rendition of a quasar at the center of an active galaxy.

Fun fact: quasars are the brightest objects in the known Universe! They’re so bright, that the light emitted from them can sometimes outshine the entirety of light emitted from all of the stars within the quasar’s host galaxy.

Is Our Milky Way An Active Galaxy?

Although our Milky Way has a supermassive black hole at its center, our galaxy is not an active galaxy.

You see, in order for a galaxy to be active, there needs to be gas and dust nearby to form an accretion disk. Currently, there’s nothing for our supermassive black hole to feast on and so it (and our galaxy’s center) remains relatively dark and inactive.

However, this hasn’t always been the case!

There’s evidence that at least twice in the past 300 years our Milky Way’s supermassive black hole (Sgr A*) has been more than a million times brighter than it is today.

And if that wasn’t cool enough—some scientists believe that our non-active Milky Way galaxy could get a kickstart in the form of an incoming collision with the Andromeda galaxy. 

During this collision, there’s a possibility that the centers of the two galaxies could collide, creating an even larger and more active supermassive black hole in the process!

If you’re worried about this incoming collision, relax! It isn’t scheduled to occur for another 4 billion years! 

An animated cartoon illustration of a supermassive blackhole's accretion disk.
A cartoon illustration of a supermassive blackhole’s accretion disk. Image Credit: AstroFan 🙂

So don’t fret quite yet for our Milky Way’s famished gravity bender—it’s merely taking a short siesta between its galactic bites!

As for us earthlings, let’s all just agree to safely observe the strange phenomena of active galaxies from the comforts of our own—slightly less hectic—place in the Universe.


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

Thank you for reading!

—Bianca, a.k.a. AstroFan

Welcome to the Neighborhood

Aubrey Henretty

Header Image: Early artistic representation of a part of the Adler Planetarium’s new exhibit, Chicago’s Night Sky.


If you traveled to a dark-sky park on a clear night to do some stargazing, you’d probably be able to see around 4,500 stars with your naked eye. On a clear night in Chicago, that number is more like 35. Here in the city, the bright lights that illuminate our buildings and streets also scatter in the atmosphere overhead—a phenomenon astronomers call “light pollution”—and make many celestial objects invisible to us. 

But a little light pollution has never stopped Chicagoans from gathering under the night sky, taking in what we can, and learning about the Universe together. In fact, Chicago has long been home to a vibrant community of stargazers, educators, artists, researchers, and storytellers inspired by what they saw in the sky. And the story of our city’s relationship to the stars is still being written. You can step inside that story—and find yourself in it—in the Adler’s newest original exhibition, Chicago’s Night Sky.

“We want people to feel that their neighborhood around them includes the sky above them,” says Michelle.

Michelle Nichols, the Adler’s director of public observing, has been helping city dwellers see their sky in a different way for years. As the founder and leader of Scopes in the City, she brings telescopes and volunteers to public spaces all over Chicagoland and watches people gasp as they lay eyes on Saturn (or a sunspot or the craters on the Moon) for the first time. Michelle was a member of the core development team for Chicago’s Night Sky, and she says its focus on people and personal connections to the sky can recreate those “Saturn moments” for museum guests.


Image: Early artistic representation of a part of the Adler Planetarium’s new exhibit, Chicago’s Night Sky, featuring a refurbished Atwood Sphere.

The exhibition celebrates Chicago stargazers past and present, professional and amateur. There’s Wallace Atwood, whose century-old, 17-foot steel sphere still whirls around friends and families and teaches them about the stars in its home at the Adler. And Frederick J. Brown, a visual artist from Chicago’s South Side, whose 1977 painting, Milky Way, found inspiration in the stars. There’s a group of local teenagers currently conducting the first-ever light-pollution survey of Chicago and another who started a public awareness campaign to help their neighbors understand what light pollution is and how they can work together to reduce it. 

Every detail of the new exhibition was designed to make people feel at home in the city and in the sky. Orilla Fetro, the Adler’s exhibit design lead, says the team took care to represent different parts of the city. “We’re not just doing the downtown skyline,” she says. “We’re doing the skyway to represent the South Side, or a bungalow that might represent the West Side.”

Throughout the space, guests will also find interactive elements that may spark their creativity or get them thinking about the ways people can change the sky we see if we work together.

Whether your night sky is clear or overcast, flooded with city lights or perfectly dark, you have an important role to play in the human traditions of looking up, sharing stories, and solving cosmic mysteries. Chicago’s Night Sky will bring you the story so far. Come help us write the next chapter.

Adler Staff Star: Meet Neil!

Neil Adam
Exhibit Technician/Graphics

What inspired you to be an Exhibits Technician?

10 years before coming to Adler, I worked at a sign shop. After hearing the Adler had an opening for someone with more of a graphics background, I was immediately interested. Knowing that the work I do could be seen by people from all over the world is an award in itself.

Neil Adam installing a graphic in Chicago’s Night Sky on a wall featuring Frederick J. Brown’s painting, “Milky Way.”

You’ve been extremely involved in building the Adler’s newest exhibit, Chicago’s Night Sky (opening November 2019). Can you give us an overview of what that process has been like for you?

Non-stop! There is a lot that goes on behind the scenes for graphics and a lot of prep work before anything can be installed.

Over the years, which exhibit has been your favorite to work on? Why?

It’s a tie between the Fabric of the Universe art collaboration and the Apollo 11 wall in the south stairwell. With the Fabric of the Universe install I got to work with some very talented artists who trusted me in the handling of their Woven Cosmos, and it looked very cool at the end. In the Apollo 11 stairwell I installed a large graphic of the Saturn V rocket, my favorite rocket since I was a kid!

Neil Adam installing a graphic on a wall in The Adler Planetarium’s new exhibit, Chicago’s Night Sky.

Why, in our opinion, is space freaking awesome?

We have something similar shown in our Cosmology gallery, but there are more stars in space than there are grains of sand on Earth. A simple perspective of just how much is out there!

Tell us a fun fact about yourself! 

I was in a band in high school called Eclipse.

Blog Subscription

Sign Up For Exclusive Content!

Need some Space in your inbox? Subscribe to our newsletter to be the first to receive the latest news on Adler programs, events, and happenings.

Resources