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physical object > naked eye object

naked eye object
subject			fact

naked eye object	is a kind of physical object
	has definition a physical object visible to the unnaided human eye
physical object	has location or center of gravity
	has angular momentum
	has mass
	has velocity
	has momentum
	has temperature
	has volume
	has extent
	has material

Kinds of naked eye object :

• Andromeda galaxy (13 facts) (M 31) - Major spiral galaxy, 2.2 million light-years from Earth. Gravitationally bound to the Milky Way with which it shares membership in the Local Group, it is currently approaching us, rather than receding as is the case for most galaxies., A spiral galaxy (kS5 in Morgan's classification) in the Local Group, about 650-700 kpc distant (M_V = -21), visible to the naked eye as a fuzzy patch in the constellation of Andromeda. Total mass about 3.1 × 10¹¹ M_sun ; i = 77°, heliocentric velocity - 180 km s^-1. Its nucleus exhibits noncircular gas motions. It is similar to but slightly larger than our Galaxy., The largest galaxy in the Local Group. Also known as the Great Spiral and M31. It is about one and a half times the size of our own galaxy, and contains at least 300 globular clusters. Two smaller, elliptical galaxies (M32 and NGC 205) lie close to it., The largest member of the local group. It is a giant spiral galaxy that lies 2.4 million light-years away.
• h and Chi Persei (8 facts) (Perseus OB1, double cluster in Perseus) - A double stellar association. It contains many young O and B stars and also many M supergiants.
• Hubble Space Telescope (23 facts) (HST, HST) - Hubble Space Telescope. A space-based reflecting telescope with a primary mirror diameter of 2.4 m (94 in) capable of high-resolution imaging from the far ultraviolet to the near infrared. A joint NASA/ESA mission. Launched in 1990 with a planned lifetime of 15 years. Encountered reduced performance when the mirror was found to have spherical aberration. Solved by the installation of corrective optics (COSTAR) in 1994.
• Hyades (9 facts)
• Magellanic Cloud (2 kinds, 34 facts) - Two relatively small, nebulous stellar systems visible only in the southern hemisphere; the larger is, however, the brightest "nebular" object in the sky. both are members of the local group of galaxies, and in fact seem to be associated, though detached, parts of the milky way system., The Large and Small Magellanic Clouds, the two nearest and largest of the galaxies that orbit the milky way. The Magellanic Clouds lie in the southern sky and cannot be seen from the United States., Two galaxies that lie close to the milky way galaxy. They are visible in the southern skies of Earth., Two small irregular (or possibly barred spiral) galaxies (satellites of the Milky Way galaxy) about 50-60 kpc (LMC, in Dorado) and 60-70 kpc (SMC, in Toucana) distant, visible to the naked eye from the southern hemisphere. Both clouds contain mainly Population I stars. The LMC contains numerous ob stars and at least 10 stars that are an order of magnitude brighter (m_v = - 9) than any supergiants known in our galaxy. It also contains several times our galaxy's concentration of interstellar matter.
• meteor (9 facts) (shooting star) - when a meteoroid collides with the atmosphere or surface of a celestial body, kinetic energy is converted to heat, light and sound, Fragment or particle that enters the Earth's atmosphere and is then destroyed through friction, becoming visible as this occurs as a momentary streak of light. At certain times of the year, meteors apparently emanating from a single area of the sky (a radiant) form meteor showers. They are thought to originate within the Solar System. See also meteorite., A "shooting star" - the streak of light in the sky produced by the transit of a meteoroid through the Earth's atmosphere; also the glowing meteoroid itself. The term "fireball" is sometimes used for a meteor approaching the brightness of Venus; the term "bolide" for one approaching the brightness of the full Moon.
• Milky Way (9 facts) - System of approximately 100000 million stars, of which our Sun is one. It is a normal spiral galaxy of class Sb, with a diameter now reckoned to be probably less than 100,000 light-years, and a strong but obscure energy source at the center (emitting infrared radiation). It is undergoing galactic rotation. Possibly one tenth of the galaxy's total mass - estimated at 1.8 × 10¹¹ solar masses - comprises interstellar gas and dust., The galaxy to which the Sun belongs. Our Galaxy is about 10¹⁰ years old and contains about 10¹¹ stars. Its mass is at least 10¹¹ M_sun, about 5-10 percent of which is in the form of gas and dust. Diameter ~ 30 kpc; thickness of nuclear bulge about 4 kpc; thickness of disk about 700-800 pc; distance between spiral arms about 1.4 kpc. M_v = - 20.5. Mean density about 0.1 M_sun per cubic parsec. Magnetic field about 3-5 × 10^-6 gauss. Total luminosity about 10⁴⁴ ergs s^-1, Our own galaxy, the second largest in the local group., A softly glowing band of light that bisects the skies of Earth, produced by light from stars and nebulae in the galactic disk.
• naked eye star (88 kinds, 964 facts) - A star visible without visual aids
• Orion Nebula (13 facts) (M 42) - A large cloud of gas and dust giving birth to young stars in the constellation Orion and visible to the naked eye. It is an HII region 1500 light-years away., An HII region about 500 pc distant, barely visible to the naked eye in the center of Orion's sword. It is undoubtedly a region where stars are being born; young O stars and many T Tauri variables are associated with it, and its members are extreme Population I. Probably no more than 20000 years old. It is also an X-ray source (3U 0527-05 and M42, NGC 1976)., The Orion Nebula, a star-forming region in the constellation Orion.
• Pleiades (11 facts) (M 45, NGC 1432)
• Praesepe (9 facts) (Beehive Cluster, M 44, NGC 2632)
• Sun (37 facts) - Star that Earth orbits. Central body of solar system. It takes about 1-10 million years for photons to diffuse from the Sun's interior to its surface. About 3% of the energy radiated is in the form of neutrinos. Every second about 655 million tons of H are being converted into 650 million tons of He. A grazing light ray is deflected 1".7 by the Sun. If the total angular momentum of the solar system were concentrated in the Sun, its equatorial rotation speed would be about 100 km s^-1.