In 1054, Chinese astronomers took notice of a “guest star” that was, for nearly a month, visible in the daytime sky. The “guest star” they observed was actually a supernova explosion, which gave rise to the Crab Nebula, a six-light-year-wide remnant of the violent event.
With an apparent magnitude of 8.4 and located 6,500 light-years from Earth in the constellation Taurus, the Crab Nebula can be spotted with a small telescope and is best observed in January. The nebula was discovered by English astronomer John Bevis in 1731, and later observed by Charles Messier who mistook it for Halley’s Comet. Messier’s observation of the nebula inspired him to create a catalog of celestial objects that might be mistaken for comets.
This large mosaic of the Crab Nebula was assembled from 24 individual exposures captured by Hubble over three months. The colors in this image do not match exactly what we would see with our eyes but yield insight into the composition of this spectacular stellar corpse. The orange filaments are the tattered remains of the star and consist mostly of hydrogen. The blue in the filaments in the outer part of the nebula represents neutral oxygen. Green is singly ionized sulfur, and red indicates doubly ionized oxygen. These elements were expelled during the supernova explosion.
A rapidly spinning neutron star (the ultra-dense core of the exploded star) is embedded in the center of the Crab Nebula. Electrons whirling at nearly the speed of light around the star’s magnetic field lines produce the eerie blue light in the interior of the nebula. The neutron star, like a lighthouse, ejects twin beams of radiation that make it appear to pulse 30 times per second as it rotates.
For more information about Hubble’s observations of M1, see:
hubblesite.org/contents/news-releases/2005/news-2005-37.html
hubblesite.org/contents/news-releases/2016/news-2016-26.html
hubblesite.org/contents/news-releases/2002/news-2002-24.html
hubblesite.org/contents/news-releases/1996/news-1996-22.html
Credit: NASA, ESA, J. Hester and A. Loll (Arizona State University)
Tags: Messier Hubble Hubble Space Telescope space NASA Crab Nebula January Sky Taurus Messier 1 M1 supernova Bevis neutron star supernova remnant astronomy SN 1054 nebula NGC 1952
Peering deep into M1, this spectacular Hubble image captures the nebula’s beating heart: the rapidly spinning pulsar at its core. Bright wisps are moving outward from the pulsar (the rightmost of the two bright stars near the center of the image) at half the speed of light to form an expanding ring. These wisps form along magnetic field lines in a gas of extremely energetic particles driven into space by the highly magnetized, rapidly rotating neutron star.
For more information about Hubble’s observations of M1, see:
hubblesite.org/contents/news-releases/2016/news-2016-26.html
Credit: NASA and ESA
Acknowledgment: J. Hester (ASU) and M. Weisskopf (NASA/MSFC)
Tags: Messier Hubble Hubble Space Telescope night sky space NASA pulsar Crab Nebula Messier 1 M1 astronomy neutron star NGC 1952 supernova remnant SN 1054 nebula
The first globular cluster to be added to the Messier catalog, M2 is located roughly 37,000 light-years from Earth in the constellation Aquarius. A globular cluster is a spherical group of stars that are bound together by their mutual gravitational attraction. M2 has a diameter of over 150 light-years and is one of the largest clusters of its kind. It was discovered in 1746 by the French astronomer Jean-Dominique Maraldi while he was observing a comet.
This Hubble image of M2’s core was created using observations taken at visible and infrared wavelengths. M2 contains over 150,000 stars. Most of the cluster’s mass is concentrated at its center, with shimmering streams of stars extending outward into space. It has an apparent magnitude of 6.3 and can be seen with the naked eye in ideal viewing conditions. The best time to observe M2 is during the month of October. Large telescopes will resolve the cluster’s individual stars.
Credit: NASA, ESA, STScI, and A. Sarajedini (University of Florida)
Tags: Messier Hubble Hubble Space Telescope night sky space NASA M2 Messier 2 Aquarius October Sky globular cluster star cluster astronomy Jean-Dominique Maraldi stars
The globular cluster M3 was the first object in the Messier catalog to be discovered by Charles Messier himself. Messier spotted the cluster in 1764, mistaking it for a nebula without any stars. This misunderstanding of M3’s nature was corrected in 1784 when William Herschel was able to resolve the cluster’s individual stars. Today it is known to contain over 500,000 stars.
M3 is notable for containing more variable stars than any other known cluster. The brightness of a variable star fluctuates with time. For some variable stars, their period relates to their intrinsic luminosity, so astronomers can use those stars’ brightness fluctuations to estimate their distances. This makes them extremely useful for measuring distances to deep-sky objects. M3 contains at least 274 variable stars.
This image of M3’s core was constructed using Hubble observations in visible and infrared light. The cluster is located 34,000 light-years from Earth in the constellation Canes Venatici. It has an apparent magnitude of 6.2 and can be spotted using a pair of binoculars. The best time to observe M3 is during May.
Credit: NASA, ESA, STScI, and A. Sarajedini (University of Florida)
Tags: Messier Hubble Hubble Space Telescope night sky space NASA M3 Messier 3 May Sky Canes Venatici astronomy star cluster globular cluster NGC 5272 stars
M4, located in the constellation Scorpius, is a huge, spherical collection of stars known as a globular cluster. Just 5,500 light-years away, it is the closest globular cluster to Earth. Because of its apparent magnitude of 5.9 and proximity to Antares, one of the brightest stars in the night sky, M4 is relatively easy to find with a small telescope. The cluster is best spotted in July.
M4 was discovered in 1746 by the Swiss astronomer Jean-Philippe Loys de Chéseaux. Home to more than 100,000 stars, the cluster is predicted to contain up to 40,000 white dwarfs — the cores of ancient, dead stars whose outer layers have drifted away into space. As white dwarfs age, they grow cooler, fainter, and more difficult to detect. Therefore, a globular cluster’s age can be inferred from the age of its faintest white dwarf. Because the stars in these clusters are some of the oldest in the universe, up to 13 billion years old, astronomers are able to use them to estimate the age of the universe.
The white dwarfs in M4 are less than one-billionth the apparent brightness of the faintest stars that can be seen with the naked eye. Even the brightest of the detected white dwarfs are no more luminous than a 100-watt light bulb seen at the moon’s distance. The faintest are comparable to a 2.5-watt night-light at the same distance.
The ancient orbs comprising M4 were captured by Hubble in both visible and infrared light. The resulting image offers a view into the center of a cluster that is more than twice the age of our solar system.
For more information about Hubble’s observations of M4, see:
www.spacetelescope.org/images/potw1236a/
hubblesite.org/contents/news-releases/2002/news-2002-10.html
Credit: ESA/Hubble & NASA
Tags: Messier 4 NGC 6121 Messier Hubble Hubble Space Telescope night sky space NASA Scorpius July Sky astronomy M4 star cluster globular cluster Jean-Philippe Loys de Cheseaux white dwarfs stars