Hubble’s updated view of NGC 3370, richer in light and detail than ever before, deepens our understanding of both the galaxy and the cosmos itself.
This new Hubble Picture of the Week highlights a galaxy that has been a favorite subject for more than two decades. Known as NGC 3370, this elegant spiral galaxy lies about 90 million light-years from Earth in the constellation Leo (The Lion). Over the years, Hubble has revisited it many times, capturing increasingly detailed views of its sweeping arms and bright central region.
Why Astronomers Keep Studying NGC 3370
What makes NGC 3370 so valuable to scientists? The galaxy contains two types of celestial objects that are essential for gauging cosmic distances: Cepheid variable stars and Type Ia supernovae. Both serve as reliable “standard candles,” allowing astronomers to calculate how far away other galaxies are with impressive accuracy.
Measuring the Universe With Pulsating Stars
Cepheid variable stars expand and contract in rhythm, changing their size and temperature as they pulsate. This process causes their brightness to rise and fall over predictable cycles lasting days to months. The key insight is that the brighter a Cepheid is, the longer it takes to complete one full pulse. By timing these light fluctuations and comparing the star’s true brightness to how bright it appears from Earth, astronomers can determine its distance — and by extension, the distance to its host galaxy.
Explosive Clues From Type Ia Supernovae
Type Ia supernovae offer another way to measure vast distances, but instead of pulsating regularly, they erupt in a single spectacular explosion. These events occur when the dense core of a dying star suddenly reignites in a burst of nuclear fusion. Because these supernovae reach nearly identical peak brightness levels, astronomers can use them as benchmarks to determine how far away they are. Observations of both Cepheid variables and Type Ia supernovae are vital for refining our understanding of how quickly the Universe is expanding.
A Sharper, More Detailed Portrait
Hubble’s earlier image of NGC 3370 was released in 2003 (see image above). The newly unveiled version zooms in closer, offering a far more intricate view of the galaxy’s spiral structure and star-filled regions. This latest image includes wavelengths of light that were not captured in the previous version, revealing additional layers of color and depth. NGC 3370 belongs to a small group of neighboring galaxies that also includes NGC 3447 and NGC 3455 — all of which have been studied by Hubble’s powerful eye on the cosmos.
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