Spring Triangle: Star Pattern Heralding a New Season
Formed by three bright stars, the Spring Triangle shines brightly in the sky, offering a perfect opportunity for stargazers to welcome the new season. Whether you're a beginner or an experienced astronomer, using tools like the Sky Tonight app can make it easier to find and track these stars. Read on to discover how to spot this celestial triangle and explore some night sky wonders along the way!
Contents
- Spring Triangle: basic facts
- Observing the Spring Triangle
- Spring Triangle stars
- Deep-sky objects in the Spring Triangle
- Spring Triangle: to sum up
Spring Triangle: basic facts
- Right ascension: 10h09 to 14h17
- Declination: +19°06' to -11°15'
- Area: 880 sq. deg.
- Brightest star: Arcturus
- Best visible in: April
The Spring Triangle connects Arcturus from Bootes, Spica from Virgo, and Regulus (or Denebola, for the smaller version) from Leo. The ecliptic crosses this star pattern, so the Moon, the Sun, and the planets frequently visit it.
The Spring Triangle is bigger than its summer counterpart: it’s almost as big across as the Winter Hexagon. Despite its size, it tends to be less well-known.
Is the Spring Triangle a constellation?
No, the Spring Triangle is not a constellation but an asterism – a prominent star pattern that doesn’t belong to the official 88 constellations.
Observing the Spring Triangle
How to find the Spring Triangle?
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Start with Arcturus: Arcturus is the brightest star in the Spring Triangle and one of the brightest stars in the sky. To locate it, first find the Big Dipper, an asterism in the constellation Ursa Major. Then, follow the curve of the Big Dipper’s handle. This will guide you directly to Arcturus.
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Find Spica: Once you’ve spotted Arcturus, follow a straight line from it to Spica. Spica is the brightest star in the constellation Virgo and is located southeast of Arcturus.
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Locate Regulus: The third star in the Spring Triangle is Regulus, located in the constellation Leo. To find it, look westward from Arcturus and Spica. You’ll see the Sickle asterism in Leo, which resembles a backward question mark. Regulus marks the bottom of this shape.
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To the east of Regulus, you can spot Denebola, marking the tail of the Lion. While it's not part of the official Spring Triangle, it can be used as an alternative to Regulus in a smaller version of the asterism.
To check if you identified all the stars correctly, open the Sky Tonight app and go to the search window. Start typing “Spring Triangle” in the search bar, and once the corresponding result appears, tap the blue target icon next to it. The app will show you the Spring Triangle’s location in your sky. Point your device up, and the map on the screen will match your sky.
When to see the Spring Triangle?
The Spring Triangle can be found in the sky around the March equinox, making it a harbinger of spring in the Northern Hemisphere – hence its name. It is the easiest to spot in April when it reaches its highest point in the night sky.
Where is the Spring Triangle visible?
It’s visible from both the Northern and Southern Hemispheres, but it is especially easy to spot in the Northern Hemisphere during spring months.
Spring Triangle stars
The Spring Triangle is made up of three prominent stars: Arcturus, Spica, and Regulus. Sometimes, Denebola is used instead of Regulus to form a smaller version of the Triangle. In this section, we'll explore the details of each star, including their types, magnitudes, and what makes them stand out in the Spring Triangle. All of them are bright enough to be seen with the naked eye.
Arcturus
- Other names: HIP 69673, HR 5340, HD 124897
- Type: red giant
- Magnitude: -0.1
- Constellation: Bootes
- Name meaning: guardian of the bear (Greek)
- Description: Arcturus is the brightest star in the constellation Bootes and one of the brightest stars in the night sky. It is a red giant, about 36 light-years away from Earth, and it shines with a reddish-orange hue. Its warm, amber color makes it one of the most recognizable stars in the night sky.
Spica
- Other names: HIP 65474, HR 5056, HD 116658
- Type: binary star
- Magnitude: 1.0
- Constellation: Virgo
- Name meaning: ear of grain (Latin)
- Description: Spica is the brightest star in the constellation Virgo and the 15th brightest star in the night sky. It is a binary star system comprising Spica A (a massive blue giant) and Spica B (a blue-white main-sequence star that is much smaller and harder to detect). Spica A emits a bluish-white color, making it appear faintly blue to the naked eye.
Regulus
- Other names: HIP 49669, HR 3982, HD 87901
- Type: quadruple star system
- Magnitude: 1.4
- Constellation: Leo
- Name meaning: little king (Latin)
- Description: Regulus is the brightest star in the constellation Leo. It marks the Lion’s heart and shines with a bluish-white hue. It is actually a multiple-star system, with at least four stars in total. The primary star, Regulus A, is a binary star that consists of the blue main sequence star of the spectral type B8 and a presumed main sequence white dwarf.
Denebola
- Other names: HIP 57632, HR 4534, HD 102647
- Type: white giant
- Magnitude: 2.1
- Constellation: Leo
- Name meaning: tail of the lion (Arabic)
- Description: Denebola is the second-brightest star in the constellation Leo, which marks the tail of the Lion. It is a main-sequence star, much cooler than our Sun, but still significantly larger. The star emits a pale white color, making it easily distinguishable in the night sky.
Deep-sky objects in the Spring Triangle
The Spring Triangle is a gateway to some notable deep-sky objects. Here, we’ll delve into three remarkable galaxy groups: the Leo Triplet, the Siamese Twins, and the Eyes Galaxies.
Leo Triplet
The Leo Triplet is a group of three spiral galaxies (M65, M66, and NGC 3628, also called the Hamburger Galaxy) gravitationally interacting with one another. When viewed from Earth, these galaxies are tilted at different angles. NGC 3628 looks like a thin line, while M65 and M66 show their spiral shapes. To view all three galaxies together, you'll need at least a 4-inch telescope. With 10x50 binoculars, you’ll typically be able to spot only M65 and M66, which will appear as faint, blurry patches.
Siamese Twins
The Siamese Twins refer to two spiral galaxies, NGC 4567 and NGC 4568, that are located close together in the sky and interact gravitationally. These galaxies are in the process of merging with each other. NGC 4567 and NGC 4568 are both located in the constellation Virgo and are around 60 million light-years away from Earth. With binoculars, you might spot the pair as faint, hazy smudges, but the full detail of the galaxies is best seen through a telescope.
Eyes Galaxies
The Eyes Galaxies refer to two spiral galaxies, NGC 4435 and NGC 4438, located close together in the constellation Virgo. NGC 4435 and NGC 4438 are about 50 million light-years away from Earth and are part of the larger Virgo Cluster of galaxies. With binoculars, you can often spot NGC 4435, but NGC 4438 might be too faint to see clearly without a telescope.
These galaxies are often called the “Eyes” because of their appearance – they resemble two bright eyes looking at you from the night sky. Many other deep-sky objects also owe their names to their unusual shape, while with others, the “name-shape” connection might not be that obvious. Can you guess the name of a nebula by its photo? Pass our quiz and see!
Spring Triangle: to sum up
The Spring Triangle is a stellar sight that heralds the arrival of spring in the Northern Hemisphere. It consists of the three bright stars – Arcturus, Spica, and Regulus. The Spring Triangle first makes its appearance in the sky around the March equinox and reaches its peak visibility in April. To easily spot this celestial pattern and the deep-sky objects within it, don’t forget to use the Sky Tonight app.
