Aladin Lite online view of the Wheel Galaxy
The Aladin Lite online view of the Wheel Galaxy, a lenticular/ring galaxy 500 million light-years from Earth, was discovered in 1941 by iconic astronomer Fritz Zwei
By far, my favorite thing as an astronomer is those rare moments when I see beautiful distant galaxies whose light left them millions to billions of years ago. The combination of sheer awe and scientific curiosity got me excited about "interstellar hunting."
In astronomy today, much of our job is to process images of the sky by writing and running programs that process large amounts of data. One disadvantage of this is that we don't always have the "hands-on" experience of observing every square inch of the universe when studying the universe. Still, I'm going to show you how I solved my miracle by looking at galaxies that only a few people have ever seen, until now.
In our observable universe alone, we estimate that there are more than 2 trillion galaxies!
Galaxies at your fingertips
Only a few decades ago, after long, cold and lonely nights of observation, astronomers had to examine photographic negatives without hesitation. In the 21st century, we can access information anytime, anywhere through the Internet.
Automated telescopes and surveys now give us so much data that we need machines to help us analyze it. In some cases, the human eye will only see what the computer thinks is interesting! Massive data hosted online, waiting for you to enjoy for free.
Cartwheel Galaxy's GALEX ultraviolet wavelength
Go online to get an atlas of the universe
Aladin Lite is one of the best online tools that can be used to observe our universe through the eyes of many different telescopes. Here, we can scan the entire sky for hidden galaxies, and even decipher information about their star number and evolution.
Let's begin our journey around the world in search of one of the most visually stunning galaxies, the Wheel Galaxy. In the Aladin interface, you can search for popular names of objects (such as "wheel galaxy") or known coordinates. The location will be centered in the interface.
The first image of the wheel galaxy we see comes from optical imaging of a digital sky survey. The colors we see represent the different color filters of this telescope. However, none of this represents the galaxy we see with the naked eye.
The general rule of thumb as an astronomer is that the "color" differences within galaxies are due to differences in the physical environment. It is important to note that things that look blue (with shorter wavelengths) are generally hotter than things that look red (with longer wavelengths).
In this galaxy, the outer ring appears to be bluer than the central red part. This may imply that star formation and stellar activity occur in the outer ring, but not in the center.
Spirals are the most iconic galaxy shapes, including many of the brightest galaxies in the nearby universe, such as the Andromeda Galaxy.
To confirm our suspicions about star formation, we can choose to look at data from different surveys and wavelengths. When young stars form, they emit large amounts of ultraviolet radiation. By changing the survey results to GALEXGR6/AIS, we are now only focusing on ultraviolet wavelengths, what a difference!
The entire central part of the Milky Way seems to "disappear" from our image. This suggests that this part may be home to older stars, with fewer stellar incubation zones.
Aladin conducted 20 different surveys. They provide sky imaging from optical, ultraviolet, infrared, X-gamma rays.
When I wander around the universe looking for interesting galaxies, I usually start with optics and find galaxies that look interesting to me. I then used different surveys to see how the images changed when looking at a particular wavelength.
Where is Universal Wally
Now that you've taken the Interstellar Hunt Crash Course, let the game begin! You can spend hours exploring incredible images and looking for interesting galaxies. I recommend looking at the image from DECalS/DR3 for maximum resolution and detail when zooming in further.
Example of a lenticular galaxy. These are galaxies that are somewhere between elliptical and spiral galaxies.
The best way is to drag the Sky Atlas directly. If you find something interesting, you can find any information we have by selecting the target icon and clicking on the object.
To help you with your galactic adventure, here are my favorite discoveries of different types of objects you might see.
Spiral galaxies usually have a central rotating disk with large spiral "arms" that curve outward from a denser central region. They are very beautiful. Our own Milky Way galaxy is a spiral galaxy.
Elliptical galaxies are largely unselected and less "flat" than spiral galaxies, and sometimes stars occupy almost a 3D ellipse. Compared to spiral galaxies, these types of galaxies tend to have older stars and less active star-forming regions.
The lenticular galaxy looks like a cosmic pancake, fairly flat and featureless in the night sky. These galaxies can be thought of as the "middle" of spiral and elliptical galaxies. Most star formation has stopped, but large amounts of dust can still be seen in lenticular galaxies.