Have you ever looked up at the night sky and wondered: How fast are those galaxies moving? The universe is constantly expanding, and galaxies are racing through space at unimaginable speeds. Astronomers use a technique called redshift and blueshift to measure whether galaxies are moving toward us or away from us—and you can try it yourself as a DIY project at home!
What Is Redshift?
Light from stars and galaxies behaves like a rainbow, made up of many colors (wavelengths). Elements like hydrogen, helium, and nitrogen leave unique fingerprints in this rainbow in the form of lines called emission or absorption lines.
- If a galaxy is moving away, these lines shift toward the red end of the spectrum → redshift.
- If it’s moving closer, they shift toward the blue end → blueshift.
By measuring how much the lines shift, we can calculate the galaxy’s redshift value (z) and even figure out its velocity—how fast it’s moving relative to Earth.
How You Can Try This at Home
In my video, I use data from the Sloan Digital Sky Survey (SDSS), which is freely available online. Here’s a quick outline of the steps:
- Visit the SDSS SkyServer Explore Tool.
- Select a galaxy, such as Z 221-50 (already loaded by default).
- Scroll to Optical Spectra and click Analyze Spectrum.
- Look for the NII emission lines (nitrogen), which are easy to spot.
- Use the “Custom Redshift” slider to align the lines with the peaks in the spectrum.
- Calculate z using the formula:
z = (Observed Wavelength−Rest Wavelength)/Rest Wavelength |
- From z, calculate velocity with:
v = z *\times* c |
(where c = speed of light = 299,792 km/s)
In the case of galaxy Z 221-50, we found a velocity of about 12,000 km/s—clearly moving away from us!
Cross-Checking with Astronomical Databases
To verify, we compared our results with SIMBAD, an online astronomical database. The professional measurement was almost the same—showing that even from home, students can get impressively close to real science results!
Why This Project Is Fun for Students
This activity is perfect for middle school and high school students (grades 7–10) because:
- It uses real telescope data (not just simulations).
- It connects directly to big scientific concepts like the expanding universe.
- It’s hands-on and feels like being a real galaxy detective.
- It combines science, math, and a little bit of technology.
Homework Challenge
Try the same method for another galaxy, LEDA 2196454, and see if your results match the official database values.
👉 Don’t forget to watch the full video for a step-by-step walkthrough:
📺 Watch on YouTube
If you enjoy projects like this, share it with your friends, or even try it as a school science experiment. The universe is out there waiting for you to explore! 🌠
