Online Resource, Article
Bessel discovered Sirius' unseen companion star long before technology allowed us to see Sirius B and even longer before quantum mechanics explained the nature of white dwarfs.
From leaf margin and arrangement to the parts of a flower and a corn seedling, take an illustrated look at plant morphology with this collection of guides.
There are 10 divisions in the plant kingdom. The largest order, flowering plants, has 235,000 species. The smallest, gingkoes, has a single species. Learn more about the orders in the kingdom Plantae.
If the Earth turns all the way around every 24 hours, then why are some days longer than others? And why do we have winter and summer? See the answers for yourself—in a matter of seconds.
From Pennsylvania to the Pacific Ocean and back again. Experience the final day of an expedition to study deep sea vents with this eyewitness account, and learn what came of the research.