Galaxy - Ginga (English spelling) galaxy

Japanese: 銀河 - ぎんが（英語表記）galaxy

A large collection of stars, interstellar matter, and dark matter. Representative examples include the Milky Way Galaxy (the galaxy to which the sun belongs) and the Andromeda Galaxy. It is surrounded by a halo of dark matter, which has a greater mass than ordinary matter such as stars. The mass and size of galaxies vary from huge to tiny, and the smaller the galaxy, the greater the number of galaxies. Large galaxies have masses of about 100 billion to several hundred billion solar masses and diameters of about 100,000 to 200,000 light years. Small galaxies can be as small as several hundred million solar masses and diameters of 10,000 light years. They come in a variety of shapes, including disk-shaped spiral galaxies with spiral arms, round elliptical galaxies, and small, dark dwarf galaxies. Galaxies form clusters. A cluster of several to several dozen galaxies is a galaxy group, a cluster of several thousand to tens of thousands of galaxies is a galaxy cluster, and these clusters further form superclusters (large-scale structures in the universe). There are hundreds of billions of galaxies in the entire universe. By measuring the distance of galaxies and combining it with redshift (the extension of the wavelength of light due to the expansion of the universe), we can learn about the structure of the universe and the acceleration or deceleration of the expansion of the universe. The Milky Way and nearby galaxies are highly evolved galaxies that were born more than 10 billion years ago, but distant galaxies with large redshifts show their ancient appearance because the speed of light is finite. By observing such galaxies, we can study galaxies immediately after their birth and their evolution. Edwin P. Hubble broadly classified galaxies into elliptical, lenticular, spiral, barred spiral, and irregular types based on the shape of galaxies in photographs, but there are many other peculiar galaxies and dwarf galaxies. Elliptical galaxies are classified according to the apparent flatness, while spiral galaxies and barred spiral galaxies are further divided according to the strength of the spiral arms and the size of the center. Lenticular galaxies are an intermediate form between elliptical galaxies and spiral nebulae, and are disk-shaped but do not have spiral arms. Irregular galaxies have an irregular shape with no regularity. Dwarf galaxies are small in both mass and size. Their distances range from as close as 150,000 light years, such as the Large and Small Magellanic Clouds, to as far as over 10 billion light years. The Andromeda Galaxy is a large spiral galaxy that is relatively close to Earth, at a distance of 2.1 million light years.

Galaxy

A land-based bomber of the Imperial Japanese Navy. Planned in 1940 as an attack aircraft capable of three missions: level bombing, dive bombing, and torpedo attacks, it was designed primarily by naval engineers. Perhaps because they were not civilian engineers, it took a lot of work to manufacture it in the factory. However, it had many excellent features, such as high speed performance, and was mass-produced by Nakajima Aircraft Company from 1943 and deployed to the front lines in 1944. A twin-engine, mid-wing monoplane aircraft with two Homare (1820 horsepower) engines, a crew of three, length 20m, width 22m, total weight 10.5t, maximum speed 551km/h, and range approximately 2000km. Armament included one 20mm cannon, one 13mm machine gun, and bomb load of 500-1000kg. 1002 units produced. Those modified into night fighters were called "Aurora" and were armed with two 20mm fixed cannon and one swivel cannon.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

恒星と星間物質，ダークマター（暗黒物質）の大集団。銀河系（太陽が属する銀河，天の川銀河）やアンドロメダ銀河などが代表例である。恒星など普通の物質よりも巨大な質量をもつダークマターのハローに囲まれている。質量や大きさは巨大なものから矮小なものまでさまざまであり，数は小さな銀河ほど多い。大きな銀河の質量は 1000億～数千億太陽質量程度，直径は 10万～20万光年ほどである。小さな銀河では数億太陽質量で直径 1万光年と小ぶりなものもある。形は渦状腕をもつ円盤状の渦状銀河（渦巻銀河），丸い形の楕円銀河，小さくて暗い矮小銀河などさまざまな形態を示す。銀河は群れをなしている。数個から数十個の銀河の群れが銀河群，数千から数万個の群れが銀河団，それらがさらに集まって超銀河団（→宇宙の大規模構造）をつくる。宇宙全体には数千億の銀河が存在する。銀河の距離を測定し，赤方偏移（宇宙の膨張による光の波長の伸び方）と組み合わせることによって，宇宙の構造や，宇宙膨張の加速や減速を知ることができる。銀河系や近傍の銀河は誕生後 100億年以上たった進化の進んだ銀河であるが，赤方偏移が大きく遠い銀河は，光速度が有限なので昔の姿を現している。このような銀河を観測することによって，誕生直後の銀河や銀河の進化を研究することができる。エドウィン・P.ハッブルは写真上での銀河の形態から，銀河を楕円型，レンズ状，渦状，棒渦状，不規則型に大別したが，これら以外の特異銀河や矮小銀河も多い。楕円銀河は見かけの扁平度に従って分類され，渦状銀河や棒渦状銀河は渦状腕の巻きつき方の強弱や中心部の大きさによって細分される。レンズ状銀河は楕円銀河と渦状星雲の中間形態で円盤状をしているが渦状腕をもたない。不規則銀河は規則性のない不定形をしている。矮小銀河は質量，大きさともに小さな銀河をさす。銀河までの距離は大小マゼラン雲のように 15万光年程度の近くから，100億光年以上という遠くまで広がっている。アンドロメダ銀河は，地球からの距離が 210万光年と比較的近い大渦状銀河である。

銀河
ぎんが

日本海軍の陸上爆撃機。水平爆撃，急降下爆撃，雷撃という3種類の任務を1機でこなせる攻撃機として 1940年に計画され，海軍の技術者が主務者となって設計された。民間技術者でなかったためか，工場での製造には手間がかかった。しかし，高速性能など優れた点も多く，1943年から中島飛行機で量産され，1944年から第一線に投入された。中翼単葉の双発機で，エンジンは誉 (1820馬力) 2，乗員3，全長 20m，全幅 22m，総重量 10.5t，最大速度時速 551km，航続距離約 2000km。武装は 20mm機関砲1，13mm機関銃1，爆弾搭載量 500～1000kg。生産機数 1002機。夜間戦闘機に改造したものを「極光」と呼び，20mm固定砲2門と旋回砲1門を装備していた。

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