This Week in Nature: January 25-31

Sirius:

Sirius

The brightest star visible from Earth, second only to the Sun, has an apparent magnitude of -1.46. (And remember, the lower the apparent magnitude, the brighter the star). Though Sirius is visible all year round, it’s so much better to view our bright stars in winter than in any other time of the year. And since the last week of January is deep in the middle of winter, it’s a perfect time to bundle up on a clear night and star gaze.

Why are stars so much brighter in winter?

During the winter months, Earth at night is facing away from the center of the Milky Way while during the summer months, Earth at night is facing toward the center. Since we are on the edge of the galaxy, the combined light of so many stars between us and the center creates a haze in the summer time that drowns out our known bright stars. During winter months, however, we are looking the opposite way – like out into the suburbs of the Milky Way. All our favorite bright stars, like Sirius, that are also in our spiral arm of the galaxy (or neighborhood, if you will) become much more clear and sharp.

 

Jupiter and Moon:

Jupiter and moon

These two celestial bodies appear together on the morning of January 28.

 

Whale songs:

whale song

Whales have two seasons – feeding season and mating season. The mating season happens during the winter months when they all migrate closer to the equator where it’s warmer and more food is available. In addition to showing off by doing tricks, flips, and other various acrobatics, males – mostly humpback whales and blue whales – will also sing.

To attract females during winter mating seasons, male whales sing intricate 30-minute songs in a range of eight octaves. Listen:

 

Image 2: Earthsky.org

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