Sản phẩm



Nhận xét

Đăng nhận xét

Bài đăng phổ biến từ blog này

Scorpion

Scorpion . Scorpions are predatory arachnids of the order Scorpiones. They have eight legs, a pair of grasping pincers and a narrow, segmented tail, often carried in a characteristic forward curve over the back and always ending with a stinger. There are over 2,500 described species. They mainly live in deserts but have adapted to a wide range of environments. Most species give birth to live young, and the female cares for the juveniles while their exoskeletons harden, transporting them on her back. Scorpions primarily prey on insects and other invertebrates, but some species take vertebrates. They use their pincers to restrain and kill prey. Scorpions themselves are preyed on by larger animals. Their venomous sting can be used both for killing prey and for defense. Only about 25 species have venom capable of killing a human. In regions with highly venomous species, human fatalities regularly occur. Scorpions with their powerful stingers appear in art, folklore, mythology, and commerc...
Đọc thêm

Sirius

Sirius . Sirius, designated Alpha Canis Majoris, is the brightest star in the night sky with a visual magnitude of −1.46. It is a close binary star system, consisting of Sirius A, a white main-sequence star, and a faint companion white dwarf, Sirius B, which was originally a massive bluish star that became a red giant before shedding its outer layers and collapsing to a white dwarf. It is one of Earth's near neighbors, at 2.6 parsecs (8.6 light-years). Sirius A is about twice as massive as the Sun and has an absolute magnitude of 1.42. It is 25 times more luminous than the Sun but has a lower luminosity than other bright stars. The system is 200 to 300 million years old. Sirius is known as the "Dog Star", due to its prominence in its constellation, Canis Major. The rising of Sirius marked the flooding of the Nile in Ancient Egypt and the "dog days" of summer for the ancient Greeks, while to the Polynesians it was important for Pacific navigation.
Đọc thêm

U-1-class submarine (Austria-Hungary)

U-1-class submarine (Austria-Hungary) . The two submarines of the U-1 class, U-1 and U-2, were built for the Austro-Hungarian Navy. Constructed according to an American design, they were launched in 1909. A diving chamber, wheels for traveling along the seabed, and other experimental features were tested extensively in sea trials. Their gasoline engines were replaced around the start of World War I over safety and efficiency concerns. The boats have been described by naval historians as obsolete by the time they were commissioned in 1911. Both submarines were mobilized briefly during the Balkan Wars, and otherwise served as training boats before 1915. From 1915 to 1918 they conducted reconnaissance cruises out of Trieste and Pola, though neither sank any enemy vessels during the war. Facing defeat in October 1918, the Austro-Hungarian government transferred the bulk of its fleet, including these submarines, to the newly formed State of Slovenes, Croats and Serbs to avoid having to...
Đọc thêm