Light Curves — Colors of the Universe
Until now, I couldn’t understand —
What’s the use of a stellar catalog at hand?
Ten million numbers it holds inside,
Celestial phones where worlds reside.
Ten million numbers, shimmering bright,
Calling the mirage, the cosmic light,
A record of flickers, a glow so grand,
The list of the cosmos at my command.
— Arseny Tarkovsky — “Star Catalog”
About Stellar Light Curves
What are light curves, and why study them? And why should ordinary people care? Now that we’ve set the questions, let’s quickly grasp the concepts, and I’ll help you develop not only a deep understanding but also a bold interest in the topic. After all, that’s the main goal of a popular science article. So, let’s begin…
“Light curves are graphs that show the brightness of an object over a certain period of time. When studying objects that change their brightness over time, such as novae, supernovae, and variable stars, a light curve is a simple yet valuable tool for a scientist.”
The study of light curves is crucial for understanding stars. It allows scientists to examine their activity, evolution, the dynamics of multiple-star systems, determine their masses and radii, and analyze pulsation processes.
How It Works
In this article, we will look at wide-angle robotic telescopes used for continuous night sky surveys — SuperWASP. These telescopes analyze variable stars, collecting information about their brightness and sending the data to researchers.
“Over 10 years, SuperWASP has generated over 30 million light curves of bright stars across the sky.”
The collected images are sent not only to scientists but also to citizen science volunteers, and anyone can become one of them. For example, SuperWASP collaborates with the Zooniverse network, where people from all over the world analyze brightness variations following special instructions. This way, they help science study the brilliant worlds of stars.
As I write this article, I noticed that on the SuperWASP project page of Zooniverse, six people are currently analyzing light curves and discussing them. As of March 19, 2025, 16,677 volunteers are participating in the project, and about 73% of the research has been completed.
Helping Discover Celestial Bodies
The study of light curves may even contribute to the discovery of life in the universe and the identification of exoplanets — planets located beyond our Solar System.
The transit method is based on analyzing a star’s brightness. When a planet passes in front of its star, its brightness slightly decreases. Regular drops in brightness allow scientists to determine the presence, size, and orbit of an exoplanet.
Analyzing Historical Star Records
Since we’ve already mentioned Zooniverse projects, it’s worth discussing another fascinating initiative related to star analysis — this time, our Sun. However, the materials for this research weren’t gathered just a few hours ago using high-tech telescopes, but rather a few centuries ago.
The Sunspot Detectives project studies the oldest records of sunspots made by past scientists using simple refracting telescopes — Galilean telescopes.
Since the 1600s, scientists have been sketching the dynamic surface of our star with a simple pencil on paper. Most of the drawings were created by the Italian priest and astronomer Angelo Secchi at the Collegio Romano in Rome, Italy, between 1853 and 1878.
“The sketches revealed sunspots, which are areas of concentrated magnetic fields. The rise and fall of sunspots create an approximately 11-year solar cycle, which is crucial for understanding the Sun’s magnetic behavior.”
You, too, can join this research and become a volunteer for this project on Zooniverse. Currently, 5,419 citizen science volunteers are contributing to this work.
How Do Light Curves Define the Colors of the Universe?
Light curves help scientists not only detect variable stars and exoplanets but also study the composition, temperature, and other characteristics of celestial objects. This method provides unique opportunities for in-depth analysis, revealing internal processes occurring within stars and other cosmic bodies.
One such process is visible when we look at space images online. Light curves play a key role in giving the Universe its colors.
By analyzing changes in brightness and color in stellar light curves, astronomers can study the matter and properties of cosmic objects. Examining spectra and brightness fluctuations, they uncover the mysteries of chemical composition, density, and even gravitational interactions in stellar systems.
Let’s explore some of the most well-known cosmic elements and their colors — a “Cosmic Palette” for Astronomers:
- Hydrogen — Often present as hydrogen gas in stars, emitting blue or white light at high temperatures.
- Helium — Stars rich in helium may have a whitish or yellowish hue.
- Carbon — Stars with a high carbon content, such as red giants, can appear reddish.
- Nitrogen — Emits in the ultraviolet spectrum, though its effect on visible colors is less pronounced.
- Oxygen — Emits light in the red and green areas of the spectrum, seen in emission nebulae.
- Iron and other heavy elements — Stars rich in iron often display yellow or orange hues.
You may have heard that images from the Hubble Space Telescope arrive on Earth in black and white. Specialists then carefully colorize nebulae and stars based on their chemical properties.
Here is an example of a fully processed Hubble Telescope image. Compare the colors in the photograph with the chemical elements I provided above.
How Can You Become a Light Curve Researcher Today?
Besides joining the volunteer science missions on Zooniverse, you can also conduct an independent experiment — using just a smartphone on a clear, sunny day.
Steps for a Simple Light Curve Experiment:
- Choose a suitable location — An open area with direct sunlight, preferably without clouds.
- Use a light measurement app — If your phone has a light sensor, install an app like Lux Light Meter. If not, use the camera to monitor brightness changes.
- Record brightness changes — Whenever you notice brightness variations (such as clouds passing by or changes in the Sun’s angle), log the readings or take pictures.
- Analyze your data — Compare your records over time to create a light curve, tracking brightness fluctuations.
This simple experiment mirrors how astronomers track star brightness changes due to shadows, clouds, or passing objects.
Thank You!
Even though a smartphone is not a scientific instrument, it can still help you feel like a scientist — whether through a light measurement experiment, participating in Zooniverse projects, or simply reading this science article about stellar light curves.
Thank you for reading!
Wishing you keen observation in your research!
The article was written in Russian and translated using ChatGPT.
