Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 28 The Ghosts of Gamma Cas Image Credit &Copyright:Guillaume Gruntz,Jean-François Bax Explanation: Gamma Cassiopeiaeshines high in northern autumn evening skies.It's the brightest spiky star in this telescopic field of viewtoward the constellation Cassiopeia.Gamma Cas shares the ethereal-looking scenewith ghostly interstellar clouds of gas and dust,IC 59 (top left) and IC 63. About 600 light-years distant,the cloudsaren't actually ghosts.They are slowly disappearing though, eroding under the influence ofenergetic radiationfrom hot and luminous gamma Cas.Gamma Cas isphysically located only 3 to 4 light-years from thenebulae.Slightly closer to gamma Cas, IC 63 is dominated byred H-alpha light emitted ashydrogen atoms ionized by the star's ultraviolet radiation recombinewith electrons.Farther from the star, IC 59 shows proportionally less H-alphaemission but more of the characteristic blue tint of dustreflected star light.The cosmic stage spans over 1 degree or 10 light-years at theestimated distance ofgamma Cas and friends. Tomorrow's picture: ghosts of the Cepheus Flare<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip...
APOD: 2023 October 26 - Orionids in Taurus Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 26 Orionids in Taurus Image Credit &Copyright:David Cortner Explanation: History's first known periodic comet,CometHalley (1P/Halley),returns to the inner Solar System every 76 years or so.The famous comet made its last appearance to the naked-eye in 1986.But dusty debris from Comet Halleycan be seen raining through planet Earth's skiestwice a year during two annual meteor showers, theEta Aquarids in Mayand theOrionids in October.In fact,an unhurried seriesof exposures captured these two bright meteors,vaporizing bits of Halley dust,during the early morning hours of October 23against a starry background along the Taurus molecular cloud.Impacting the atmosphere at about 66 kilometers per second theirgreenishstreaks point back to theshower's radiant just northof Orion's bright star Betelgeuse off the lower left side ofthe frame.The familiar Pleiadesstar cluster anchors the dusty celestial scene atthe right. Tomorrow's picture: 2P/Encke<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy and Important NoticesA service of:ASD atNASA /GSFC,NASA ScienceActivation& Michigan Tech....
Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 27 Encke and the Tadpoles Image Credit &Copyright:Dan Bartlett Explanation: History's second known periodic comet isComet Encke (2P/Encke).As it swings through the innerSolar System, Encke'sorbit takes it from an aphelion, its greatest distance from the Sun,inside the orbit of Jupiter to aperihelion just inside the orbit of Mercury.Returning to its perihelion every 3.3 years, Encke has the shortestperiod of the Solar System'smajor comets.Comet Encke is also associated with(at least)two annual meteor showers onplanet Earth, theNorth and South Taurids.Both showers are active in late October and early November.Their two separate radiants lie near bright star Aldebaran in the head-strongconstellation Taurus.A faint comet, Encke was captured inthis telescopic field of viewimaged on the morning of August 24.Then, Encke's pretty greenish coma was close on the sky to the young, embedded star cluster and light-years long,tadpole-shapedstar-forming clouds in emission nebula IC 410.Now near bright star Spicain Virgo Comet Encke passed its 2023 perihelion only five days ago,on October 22. Tomorrow's picture: mostly a ghostly weekend<| Archive| Submissions | Index| Search| Calendar| RSS| Education|...
Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 26 Orionids in Taurus Image Credit &Copyright:David Cortner Explanation: History's first known periodic comet,CometHalley (1P/Halley),returns to the inner Solar System every 76 years or so.The famous comet made its last appearance to the naked-eye in 1986.But dusty debris from Comet Halleycan be seen raining through planet Earth's skiestwice a year during two annual meteor showers, theEta Aquarids in Mayand theOrionids in October.In fact,an unhurried seriesof exposures captured these two bright meteors,vaporizing bits of Halley dust,during the early morning hours of October 23against a starry background along the Taurus molecular cloud.Impacting the atmosphere at about 66 kilometers per second theirgreenishstreaks point back to theshower's radiant just northof Orion's bright star Betelgeuse off the lower left side ofthe frame.The familiar Pleiadesstar cluster anchors the dusty celestial scene atthe right. Tomorrow's picture: 2P/Encke<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy and Important NoticesA service of:ASD atNASA /GSFC,NASA ScienceActivation& Michigan Tech. U.
APOD: 2023 October 20 - Galaxies and a Comet Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 20 Galaxies and a Comet Image Credit &Copyright:Dan Bartlett Explanation: Galaxies abound in this sharptelescopic image recorded onOctober 12 in dark skies over June Lake, California.The celestial scene spans nearly 2 degrees within the boundariesof the well-trained northern constellation Canes Venatici.Prominent at the upper left 23.5 million light-years distantis big, beautiful spiral galaxy NGC 4258,known to some as Messier 106.Eye-catching edge-on spiral NGC 4217 is above and right of centerabout 60 million light-years away.Just passing through the pretty field of view is cometC/2023 H2 Lemmon,discovered last April in image data from theMount Lemmon Survey.Here the comet sports more of a lime green coma though, alongwith a faint, narrow ion tail stretchingtoward the top of the frame.Thisvisitor to the inner Solar Systemis presently less than 7 light-minutes away and still difficult to spotwith binoculars, but it's growing brighter.Comet C/2023 H2 Lemmonwill reachperihelion, its closest point to the Sun, on October 29 andperigee, its closest to our fair planet, on November 10as it transitions from morning to evening...
Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 21 Quarter Moons Image Credit &Copyright:Marcella Giulia Pace Explanation: Half way between New Moon and Full Moon isthe Moon's first quarter phase.That's a quarter of the way around itsmoonthly orbit.At the first quarter phase, halfthe Moon's visible sideis illuminated by sunlight.For the Moon's third quarter phase, half way betweenFull Moon and New Moon, sunlight illuminates the otherhalf of the visible lunar disk.At both first and third quarter phases,the terminator, or shadow line separating the lunar night and day,runs down the middle.Near the terminator,long shadows bring lunar craters andmountains in to sharp relief, making the quarter phases a good timeto observe the Moon.But in case you missed some,all the quarter phases of the Moonand their calendar dates during 2022can be found in this well-planned array of telephoto images.Of course, you can observea first quarter Moon tonight. International:Observe the Moon Night Tomorrow's picture: ghostly northern lights<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy...
Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 20 Galaxies and a Comet Image Credit &Copyright:Dan Bartlett Explanation: Galaxies abound in this sharptelescopic image recorded onOctober 12 in dark skies over June Lake, California.The celestial scene spans nearly 2 degrees within the boundariesof the well-trained northern constellation Canes Venatici.Prominent at the upper left 23.5 million light-years distantis big, beautiful spiral galaxy NGC 4258,known to some as Messier 106.Eye-catching edge-on spiral NGC 4217 is above and right of centerabout 60 million light-years away.Just passing through the pretty field of view is cometC/2023 H2 Lemmon,discovered last April in image data from theMount Lemmon Survey.Here the comet sports more of a lime green coma though, alongwith a faint, narrow ion tail stretchingtoward the top of the frame.Thisvisitor to the inner Solar Systemis presently less than 7 light-minutes away and still difficult to spotwith binoculars, but it's growing brighter.Comet C/2023 H2 Lemmonwill reachperihelion, its closest point to the Sun, on October 29 andperigee, its closest to our fair planet, on November 10as it transitions from morning to evening northern skies. Tomorrow's picture:...
APOD: 2023 October 13 - Hydrogen Clouds of M33 Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 13 Hydrogen Clouds of M33 Image Credit &Copyright:Reinhold Wittich Explanation: Gorgeous spiral galaxy Messier 33 seems to have more than its fair share ofglowing hydrogen gas.A prominent member of the local group of galaxies, M33 is alsoknown as the Triangulum Galaxy andlies a mere 3 million light-years away. The galaxy's central 30,000 light-years or so are shown in thissharp galaxy portrait.The portrait features M33'sreddish ionized hydrogen clouds orHII regions.Sprawling along loose spiral arms that wind toward the core,M33's giant HII regionsare some of the largest known stellar nurseries,sites of the formation of short-lived but very massive stars.Intense ultraviolet radiation from the luminous, massive stars ionizesthe surrounding hydrogen gas and ultimately produces thecharacteristic red glow.In this image, broadband data were combinedwith narrowband data recorded through a hydrogen-alpha filter.That filter transmits the light of the strongest visible hydrogenemission line. Tomorrow's picture: ring around the Sun<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific...
Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 14 Circular Sun Halo Image Credit &Copyright:Vincenzo Mirabella Explanation: Want to see a ring around the Sun?It's easy to doin daytime skies around the world.Created by randomly oriented ice crystals in thin high cirrus clouds,circular 22 degree halos are visible much more often than rainbows.This one wascaptured by smart phonephotographyon May 29, 2021 near Rome, Italy.Carefullyblocking the Sun,for example with a finger tip,is usually all that it takes to reveal the common bright halo ring.The halo's characteristic angular radius is about equalto the span of your hand, thumb to little finger,at the end of your outstretched arm. Want to see aring of fire eclipse?That's harder.The spectacular annular phase oftoday's (October 14) solar eclipse,known as a ring of fire,is briefly visible only when standing alongthe Moon's narrow shadow track that passes over limited parts ofNorth, Central, and South America.The solar eclipse is partial though, when seenfrom broader regions throughout the Americas. Tomorrow's picture: Sun Day<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert...
Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 13 Hydrogen Clouds of M33 Image Credit &Copyright:Reinhold Wittich Explanation: Gorgeous spiral galaxy Messier 33 seems to have more than its fair share ofglowing hydrogen gas.A prominent member of the local group of galaxies, M33 is alsoknown as the Triangulum Galaxy andlies a mere 3 million light-years away. The galaxy's central 30,000 light-years or so are shown in thissharp galaxy portrait.The portrait features M33'sreddish ionized hydrogen clouds orHII regions.Sprawling along loose spiral arms that wind toward the core,M33's giant HII regionsare some of the largest known stellar nurseries,sites of the formation of short-lived but very massive stars.Intense ultraviolet radiation from the luminous, massive stars ionizesthe surrounding hydrogen gas and ultimately produces thecharacteristic red glow.In this image, broadband data were combinedwith narrowband data recorded through a hydrogen-alpha filter.That filter transmits the light of the strongest visible hydrogenemission line. Tomorrow's picture: ring around the Sun<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Phillip NewmanSpecific rights apply.NASA WebPrivacy Policy...
APOD: 2023 October 12 - Mu Cephei Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 12 Mu Cephei Image Credit &Copyright:David Cruz Explanation: Mu Cepheiis a very large star.An M-class supergiant some 1500 times the size of the Sun, it is one ofthe largest stars visible to the unaided eye,and even one of the largest in the entire Galaxy.If it replaced the Sun inour fair Solar System,Mu Cephei would easily engulf Mars and Jupiter.Historically known asHerschel's Garnet Star,Mu Cephei is extremely red.Approximately 2800 light-years distant, the supergiant isseen near the edge of reddish emission nebulaIC 1396 towardthe royal northern constellation Cepheus inthis telescopic view.Much cooler and hence redder than the Sun,this supergiant's light is further reddened by absorption andscattering due to intervening dust within the Milky Way.A well-studied variable starunderstood to be in a late phaseof stellar evolution, Mu Cephei is a massive star too,destinedto ultimately explode as a core-collapsesupernova. APOD editor to speak: in Houghton, Michigan tonight, Thursday, October 12, at 6 pm Tomorrow's picture: pixels in space<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors &...
Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 12 Mu Cephei Image Credit &Copyright:David Cruz Explanation: Mu Cepheiis a very large star.An M-class supergiant some 1500 times the size of the Sun, it is one ofthe largest stars visible to the unaided eye,and even one of the largest in the entire Galaxy.If it replaced the Sun inour fair Solar System,Mu Cephei would easily engulf Mars and Jupiter.Historically known asHerschel's Garnet Star,Mu Cephei is extremely red.Approximately 2800 light-years distant, the supergiant isseen near the edge of reddish emission nebulaIC 1396 towardthe royal northern constellation Cepheus inthis telescopic view.Much cooler and hence redder than the Sun,this supergiant's light is further reddened by absorption andscattering due to intervening dust within the Milky Way.A well-studied variable starunderstood to be in a late phaseof stellar evolution, Mu Cephei is a massive star too,destinedto ultimately explode as a core-collapsesupernova. APOD editor to speak: in Houghton, Michigan tonight, Thursday, October 12, at 6 pm Tomorrow's picture: pixels in space<| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert...
APOD: 2023 October 6 - Edwin Hubble Discovers the Universe Discover the cosmos!Each day a different image or photograph of our fascinating universe isfeatured, along with a brief explanation written by a professional astronomer. 2023 October 6 Edwin Hubble Discovers the Universe Image Credit & Copyright: CourtesyCarnegie Institution for Science Explanation: How big is our universe?This question, among others, was debated by two leading astronomers in 1920 in what has sincebecome known as astronomy'sGreat Debate. Many astronomers then believed that our Milky Way Galaxy was the entire universe. Many others, though, believed that our galaxy was just one of many. In the Great Debate, each argument was detailed, but no consensus was reached. The answer came over three years later with the detected variation of single spot in the Andromeda Nebula, as shown on the original glass discovery plate digitally reproduced here.When EdwinHubble compared images, he noticed that thisspot varied, and on October 6, 1923wrote "VAR!" on the plate. The best explanation, Hubble knew, was that this spot was the image of a variable star that was very far away.So M31 was really the Andromeda Galaxy -- a galaxy possibly similar to our own. Annotated 100 years ago, the featured image...