LATEST ASTRONOMY VIDEOS
LATEST ASTRONOMY VIDEOS
Cosmic Wonders
The Bubble Nebula: Winds & Radiation from a Massive Star
HubbleSite: https://hubblesite.org/contents/media...
- YouTube: https://youtu.be/teJ01WXYp6M
A Flight Through the CANDELS Ultra Deep Survey Field
YouTube: https://youtu.be/SUyDcyHpFhc
A Rose of Galaxies: Interacting Galaxies Arp 273
YouTube: https://youtu.be/4t3Eyg4zGeA
Sculpture Garden of Gas and Dust: Core of the Lagoon Nebula
YouTube: https://youtu.be/FhpMyaJ3ahc
Stellar Greetings from Globular Cluster M79
YouTube: https://youtu.be/EtHArjpbfT
Hickson Compact Group 40: A Flight Through Interacting Galaxies
- YouTube: https://youtu.be/_-QZ15QJrfs
The Red Bubble: Supernova Remnant SNR 0509-67.5
- YouTube: https://youtu.be/96YLkY-N0o4
Exploring the Structure of the Ring Nebula
YouTube: https://youtu.be/_a94pl2lrYM
Star Clusters in CollisionB
YouTube: https://youtu.be/1ekzgnn_iIw
Blast Wave from a Stellar Explosion: Simulation of Supernova 1987A YouTube: https://youtu.be/MBGP5DMNlSo
Eta Carinae: The Great Eruption of a Massive Star
YouTube: https://youtu.be/07hqULmszC8
A Horse of a Different Color: The Gaseous Landscape of the Horsehead Nebula in Infrared
YouTube: https://youtu.be/drTtTsevWBs
Celestial Fireworks: Star Cluster Westerlund 2
YouTube: https://youtu.be/kYhmwT_NJzU
Flight Through the Orion Nebula in Visible Light
YouTube: https://youtu.be/KELd9edjw0c
Crash of the Titans: Milky Way & Andromeda Collision
- YouTube: https://youtu.be/-WoLSL3EDEs
Celestial Snow Angel: Star-forming Region Sharpless 2-106
YouTube: https://youtu.be/YzfbOECnuQg
Flyby of the Whirlpool Galaxy
YouTube: https://youtu.be/ikdXEcMIjgA
Cosmic Reef: NGC 2014 & NGC 2020
YouTube: https://youtu.be/WoFQTYUSi_U
Crab Nebula
Crab Nebula
- Crab Nebula, probably the most intensely studied bright nebula, in the constellation Taurus, about 6,500 light-years from Earth.
- Roughly 10 light-years in diameter, it is assumed to be the remnant of a supernova observed by Chinese and other astronomers first on July 4, 1054.
- The supernova was visible in daylight for 23 and at night for almost 2 years.
- In 1758 it was the first object listed (M1) in Charles Messier’s catalog of nebulous objects.
- It acquired its name, suggested by its form, in the mid-19th century. In 1921 it was discovered to be still expanding; the present rate is about 1,100 km (700 miles) per second.
- The Crab is one of the few astronomical objects from which radiation has been detected over the entire measurable spectrum, from radio waves through infrared and visible wavelengths to ultraviolet, X-rays, and gamma rays.
- In the late 1960s the Crab pulsar ,thought to be the collapsed remnant of the supernova was discovered near the centre of the nebula.
- The pulsar, which flashes in radio, visible, X-ray, and gamma-ray wavelengths at 30 times per second, provides the energy that allows the nebula to glow.
Classes of nebulae
- All nebulae observed in the Milky Way Galaxy are forms of interstellar matter—namely, the gas between the stars that is almost always accompanied by solid grains of cosmic dust
- Their appearance differs widely, depending not only on the temperature and density of the material observed but also on how the material is spatially situated with respect to the observer.
- Their chemical composition, however, is fairly uniform; it corresponds to the composition of the universe in general in that approximately 90 percent of the constituent atoms are hydrogen and nearly all the rest are helium, with oxygen, carbon, neon, nitrogen, and the other elements together making up about two atoms per thousand.
- On the basis of appearance, nebulae can be divided into two broad classes: dark nebulae and bright nebulae.
- Dark nebulae appear as irregularly shaped black patches in the sky and blot out the light of the stars that lie beyond them.
- Bright nebulae appear as faintly luminous glowing surfaces; they either emit their own light or reflect the light of nearby stars.
- Dark nebulae are very dense and cold molecular clouds; they contain about half of all interstellar material.
- Bright nebulae are comparatively dense clouds of gas within the diffuse interstellar medium.
They have several subclasses: (1) reflection nebulae, (2) H II regions, (3) diffuse ionized gas, (4) planetary nebulae, and (5) supernova remnants. - Reflection nebulae reflect the light of a nearby star from their constituent dust grains. The gas of reflection nebulae is cold, and such objects would be seen as dark nebulae if it were not for the nearby light source.H II regions are clouds of hydrogen ionized (separated into positive H+ ions and free electrons) by a neighboring hot star.
- Diffuse ionized gas, so pervasive among the nebular clouds, is a major component of the Galaxy.
- Planetary nebulae are ejected from stars that are dying but are not massive enough to become supernovae—namely, red giant stars.
- Supernova remnants are the clouds of gas expanding at speeds of hundreds or even thousands of kilometres per second from comparatively recent explosions of massive stars.
- If a supernova remnant is younger than a few thousand years, it may be assumed that the gas in the nebula was mostly ejected by the exploded star.
- Otherwise, the nebula would consist chiefly of interstellar gas that has been swept up by the expanding remnant of older objects.


















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