Spring Constellation Spotlight: Ursa Major

With the arrival of spring, a season of transformation is underway—bringing warmer weather, blooming flowers, and clearer night skies where prominent constellations come into view. Among these is Ursa Major, "The Great Bear," one of the most renowned circumpolar constellations in the Northern Hemisphere.

Within Ursa Major lies the easily recognizable asterism known as the Big Dipper, a striking formation of seven bright stars resembling a saucepan. Although the Big Dipper itself is not a constellation, it stands out as one of the most familiar star patterns and has long served as a reliable navigational guide to locate the North Star, Polaris.

Ursa Major is more than just a striking star formation—it also hosts a variety of celestial wonders, including bright galaxies, a planetary nebula, and brilliant stars. Let's dive deeper and explore what makes this constellation so extraordinary.

 

 

Mythology

"Ursa Major" is Latin and translates to "The Great Bear." Many constellations have Latin names, as they were cataloged and named during a time when Latin was the predominant scientific language. According to Greek mythology, Ursa Major represents Callisto, a beautiful nymph and follower of Artemis, the goddess of the hunt. Callisto vowed to remain chaste, but Zeus, disguised as Artemis, seduced her. When Callisto's pregnancy was discovered, Artemis punished her by transforming her into a bear. Years later, Callisto's son, Arcas, unknowingly encountered her while hunting. To prevent an unfortunate tragedy, Zeus placed Callisto and Arcas in the sky as constellations—Callisto as Ursa Major and Arcas as Ursa Minor, the Little Dipper, or Little Bear.

 

 

How to locate Ursa Major

Ursa Major occupies 1,280 square degrees, making it the third-largest constellation in the night sky. Here's how you can easily locate it:

• Find the Big Dipper: Look for a group of seven bright stars forming a "saucepan" outline—four bright stars make up the bowl, and three stars form the handle (the Great Bear's tail).
• Face North: The Big Dipper is circumpolar and is visible year-round in the Northern Hemisphere. It appears highest in the sky during the Spring. In the Fall, the Dipper is closer to the horizon.
• Use the Pointer Stars: The two stars of the outer bowl, Dubhe and Merak, are known as the "pointer stars." Draw an imaginary line through them, and they will point to Polaris, the North Star. Polaris is the tail-end star in the constellation Ursa Minor. This is the easiest way to locate your position, as Polaris will stay in the same part of the sky year-round.
• Look beyond the Big Dipper: Use a star map or Celestron's free SkyPortal Powered by SkySafari™ app for Celestron telescope owners to explore and learn the other stars that help form the shape of the large Bear.

 

 

Prominent Stars

Ursa Major contains 22 formally named bright and notable stars, many forming the famous Big Dipper asterism. Here are the key stars:

• Dubhe (Alpha Ursae Majoris): The second brightest star in Ursa Major shines with an apparent magnitude of +1.79, marking the Bear's back. It's one of the "pointer stars" used to locate Polaris, the North Star.
• Merak (Beta Ursae Majoris): Another pointer star, located next to Dubhe in the Big Dipper's bowl. It has an apparent magnitude of +2.34.
• Alioth (Epsilon Ursae Majoris): The brightest star in the Big Dipper's handle—and the third brightest in the constellation overall—shines at an apparent magnitude of +1.75.
• Mizar (Zeta Ursae Majoris): This well-known optical "double star" is paired with Alcor in the handle of the Big Dipper, with apparent magnitudes of +2.22 and +4.00 respectively. Although Mizar and Alcor appear close together in the sky, they are not gravitationally bound to each other. Mizar, however, is actually a binary star system (Mizar A and Mizar B).
• Alkaid (Eta Ursae Majoris): With an apparent magnitude of +1.85, Alkaid is the third-brightest star in Ursa Major and lies at the tip of the Big Dipper's handle.
• Phecda (Gamma Ursae Majoris): Located at the bottom of the Big Dipper's bowl, Phecda has an apparent magnitude of +2.44.
• Megrez (Delta Ursae Majoris): With an apparent magnitude of +3.32, Megrez is the dimmest star in the Big Dipper and links the bowl to the handle. Its Arabic name means "root of the Great Bear's tail."
• Winnecke 4, also known as Messier 40 (M40), is an optical "double star" consisting of two stars that appear close together in the sky but are not physically connected. It is one of the few Messier objects that are not deep-sky objects. The brighter star has a magnitude of about +9.65, while the fainter star has a magnitude of +10.10.

 

Nebulae

Messier 97 (The Owl Nebula): Also known as NGC 3587, Pierre Méchain discovered this planetary nebula in 178. Charles Messier added it to his catalog that same year. It is a fascinating object, and its name comes from the appearance of owl-like "eyes." It lies approximately 2,030 light-years from Earth with an apparent magnitude of +9.9, making it visible through small telescopes under good conditions. The Owl Nebula formed when a dying star expelled its outer layers into space. The star's remaining core is now a hot white dwarf, estimated to be around 8,000 years old. M97 is a favorite target among amateur astronomers. Look for it near the star Merak.

 

 

 

Galaxies

	M51 (The Whirlpool Galaxy) Though technically not part of Ursa Major but the neighboring constellation Canes Venatici, this stunning galaxy is a close neighbor of the Great Bear. Like Polaris, observers often find M51 using the Big Dipper as a reference point. M51 lies near the star Alkaid, the easternmost star of the Dipper. Charles Messier discovered M51 in 1773, while Pierre Méchain discovered its companion galaxy, NGC 5195, in 1781. With an apparent magnitude of +8.4, M51's face-on view, impressive spiral arms, and connecting companion galaxy, as seen from our perspective on Earth, make it a popular target for binoculars and telescopes in dark skies.
	M81 (Bode's Nebula) One of the most brilliant spiral galaxies in the sky, M81’s well-defined spiral arms make it both easy and rewarding to observe. Johann Elert Bode discovered it along with neighboring galaxy M82 in 1774 and described it as a "nebulous patch." Charles Messier added M81 to his catalog in 1781. With a total visual magnitude of 6.8, M81 can be seen in binoculars and small telescopes in dark skies.
	M82 (Cigar Galaxy) Located near M81, M82 is a peculiar, elongated-shaped galaxy undergoing heavy star formation, giving it the nickname "Cigar Galaxy." Due to the high star formation rate, its core is extremely luminous and shines brightly, especially in infrared wavelengths. Messier 82 is relatively bright, at an apparent magnitude of +8.4. It can be seen along with neighboring M81 in the same field of view of binoculars and low-power wide-angle telescopes in dark skies. M81 is gravitationally bound to M82.
	M101 (Pinwheel Galaxy) This large, picturesque face-on spiral galaxy that resembles a pinwheel is a favorite target of astroimagers. Messier 101 was discovered by Pierre Méchain in 1781, and Charles Messier added it to his catalog later that year. It lies approximately 21 million light-years away from Earth and has a diameter of about 170,000 light-years, making it larger than our Milky Way. It has an apparent magnitude of +7.9 but features low surface brightness, requiring dark skies to view it in telescopes. During the 20th century, M101 produced three supernovae:  SN 1909A, SN 1951H, and SN 1970G.
	M108 (Surfboard Galaxy) Also known as NGC 3556, this galaxy appears as an almost edge-on barred spiral galaxy from our perspective on Earth. It was discovered by Pierre Méchain around 1782 but was not added to the Messier catalog until the 1950s. M108 has an apparent visual magnitude of +9.96 and lies about 46 million light-years away. This galaxy boasts an estimated 125 billion solar masses and about 290 globular clusters! Its core hosts a supermassive black hole with approximately 24 million solar masses.
	M109 Also known as NGC 3992, M109 is a barred spiral galaxy discovered by Pierre Méchain in 1781. Charles Messier listed it in his catalog in 1783, but it was not widely accepted into the "official" Messier catalog until the 1950s. M109 has an apparent magnitude of +9.6, lies approximately 84 million light-years from Earth, and is the most distant object in the Messier catalog. It features an inner ring structure surrounding its central bar and is home to a trillion stars. The Galaxy has three known satellite galaxies: UGC 6923, UGC 6940, and UGC 6969. In 1956, a supernova, SN 1956A, was discovered and reached a magnitude of +12.3. M109 is located near the star Phecda in the Big Dipper and is a popular target for visual observers and astroimagers.
	NGC 2976 A strange dwarf galaxy in the M81 Group of galaxies. It was discovered by William Herschel in 1801 and has a unique disk appearance, lacking a well-defined spiral structure and a central bulge. This Galaxy's oval shape and some noticeable features are visible through medium to large telescopes in dark skies. It has an apparent magnitude of +10.8. A smaller telescope will reveal a faint glow.
	NGC 3077 An unusual elliptical galaxy within the M81 Group of galaxies. Discovered by William Herschel in 1801, it was initially identified as a Seyfert galaxy because of its active nucleus, but it no longer meets the criteria for modern Seyfert classification. With an apparent magnitude of +10.6, this galaxy appears as a faint, oval-shaped blur, visible through small to medium-sized telescopes under dark skies.
	NGC 3953 A barred spiral galaxy discovered by Pierre Méchain in 1781, NGC 3953 features an inner ring structure that encircles its small central bar and spiral arms. Resembling M109 (NGC 3992), it is located approximately 1 degree to the southeast. Two supernovae have been observed in this galaxy: SN 2001dp and SN 2006bp. With an apparent magnitude of +10.8, NGC 3953 is visible in telescopes under dark skies.

 

 

Let's Go Observing!

 

Ursa Major and its prominent asterism, the Big Dipper, form one of the most beautiful and iconic star patterns in the Northern Hemisphere. The Big Dipper's distinctive shape has been a reliable navigational guide for generations of sailors and travelers, enabling them to locate Polaris and identify true north. From the tranquility of a dark-sky setting, you can easily follow the constellation's stars and envision the Great Bear. For observers and astrophotographers alike, Ursa Major reveals a wealth of deep-sky treasures, particularly galaxies. Whether you’re exploring its scientific importance, tracing its mythological roots, or marveling at its wonders through the eyepiece, Ursa Major offers a lasting connection to the cosmos.