APOD Timeline
A Night Sky over the Tatra Mountains
Sept. 11, 2024
A natural border between Slovakia and Poland is the Tatra Mountains. A prominent destination for astrophotographers, the Tatras are the highest mountain range in the Carpathians. In the featured image taken in May, one can see the center of our Milky Way galaxy with two of its famous stellar nurseries, the Lagoon and Omega Nebula, just over the top of the Tatras. Stellar nurseries are full of ionized hydrogen, a fundamental component for the formation of Earth-abundant water. As a fundamental ingredient in all known forms of life, water is a crucial element in the Universe. Such water can be seen in the foreground in the form of the Bialka River. Portal Universe: Random APOD Generator
M31: The Andromeda Galaxy
Sept. 8, 2024
The most distant object easily visible to the unaided eye is M31, the great Andromeda Galaxy. Even at some two and a half million light-years distant, this immense spiral galaxy -- spanning over 200,000 light years -- is visible, although as a faint, nebulous cloud in the constellation Andromeda. A bright yellow nucleus, dark winding dust lanes, and expansive spiral arms dotted with blue star clusters and red nebulae, are recorded in this stunning telescopic image which combines data from orbiting Hubble with ground-based images from Subaru and Mayall. In only about 5 billion years, the Andromeda galaxy may be even easier to see -- as it will likely span the entire night sky -- just before it merges with, or passes right by, our Milky Way Galaxy. Teachers & Students: Ideas for using APOD in the classroom
NGC 247 and Friends
Sept. 5, 2024
About 70,000 light-years across, NGC 247 is a spiral galaxy smaller than our Milky Way. Measured to be only 11 million light-years distant it is nearby though. Tilted nearly edge-on as seen from our perspective, it dominates this telescopic field of view toward the southern constellation Cetus. The pronounced void on one side of the galaxy's disk recalls for some its popular name, the Needle's Eye galaxy. Many background galaxies are visible in this sharp galaxy portrait, including the remarkable string of four galaxies just below and left of NGC 247 known as Burbidge's Chain. Burbidge's Chain galaxies are about 300 million light-years distant. NGC 247 itself is part of the Sculptor Group of galaxies along with shiny spiral NGC 253.
NGC 6995: The Bat Nebula
Sept. 4, 2024
Can you see the bat? It haunts this cosmic close-up of the eastern Veil Nebula. The Veil Nebula itself is a large supernova remnant, the expanding debris cloud from the death explosion of a massive star. While the Veil is roughly circular in shape and covers nearly 3 degrees on the sky toward the constellation of the Swan (Cygnus), NGC 6995, known informally as the Bat Nebula, spans only 1/2 degree, about the apparent size of the Moon. That translates to 12 light-years at the Veil's estimated distance, a reassuring 1,400 light-years from planet Earth. In the composite of image data recorded through narrow band filters, emission from hydrogen atoms in the remnant is shown in red with strong emission from oxygen atoms shown in hues of blue. Of course, in the western part of the Veil lies another seasonal apparition: the Witch's Broom Nebula. Teachers & Students: Ideas for using APOD in the classroom
A Triangular Prominence Hovers Over the Sun
Sept. 2, 2024
Why is there a triangle hovering over the Sun? Although the shape is unusual, the type of structure is not: it is part of an evolving solar prominence. Looping magnetic fields on the Sun channel the flow of energetic particles, sometimes holding glowing gaseous structures aloft for months. A prominence glows brightly because it contains particularly hot, dense, or opaque solar plasma. The surprising triangular structure occurred last week. Larger than our Earth, the iconic prominence was imaged by several solar photographers and documented by NASA's Solar Dynamic Observatory to form and violently dissipate in about a day. The featured image was captured in a color of red light emitted strongly by hydrogen. Below, solar fibrils carpet the Sun's chromosphere, while the background sky is so faint in comparison that no stars are visible. Our Sun's surface has been quite active this year.
IC 5146: The Cocoon Nebula
Aug. 19, 2024
Inside the Cocoon Nebula is a newly developing cluster of stars. Cataloged as IC 5146, the beautiful nebula is nearly 15 light-years wide. Soaring high in northern summer night skies, it's located some 4,000 light years away toward the constellation of the Swan (Cygnus). Like other star forming regions, it stands out in red, glowing, hydrogen gas excited by young, hot stars, and dust-reflected starlight at the edge of an otherwise invisible molecular cloud. In fact, the bright star found near the center of this nebula is likely only a few hundred thousand years old, powering the nebular glow as it clears out a cavity in the molecular cloud's star forming dust and gas. A 48-hour long integration resulted in this exceptionally deep color view tracing tantalizing features within and surrounding the dusty stellar nursery.
A Solar Prominence Eruption from SDO
Aug. 18, 2024
One of the most spectacular solar sights is an erupting prominence. In 2011, NASA's Sun-orbiting Solar Dynamic Observatory spacecraft imaged an impressively large prominence erupting from the surface. The dramatic explosion was captured in ultraviolet light in the featured time lapse video covering 90 minutes, where a new frame was taken every 24 seconds. The scale of the prominence is huge -- the entire Earth would easily fit under the flowing curtain of hot gas. A solar prominence is channeled and sometimes held above the Sun's surface by the Sun's magnetic field. A quiescent prominence typically lasts about a month and may erupt in a Coronal Mass Ejection (CME) expelling hot gas into the Solar System. The energy mechanism that creates a solar prominence is a continuing topic of research. Our Sun is again near solar maximum and so very active, featuring numerous erupting prominences and CMEs, one of which resulted in picturesque auroras just over the past week.
Sky Full of Arcs
Aug. 17, 2024
On August 11 a Rocket Lab Electron rocket launched from a rotating planet. With a small satellite on board its mission was dubbed A Sky Full of SARs (Synthetic Aperture Radar satellites), departing for low Earth orbit from Mahia Peninsula on New Zealand's north island. The fiery trace of the Electron's graceful launch arc is toward the east in this southern sea and skyscape, a composite of 50 consecutive frames taken over 2.5 hours. Fixed to a tripod, the camera was pointing directly at the South Celestial Pole, the extension of planet Earth's axis of rotation in to space. But no bright star marks that location in the southern hemisphere's night sky. Still, the South Celestial Pole is easy to spot. It lies at the center of the concentric star trail arcs that fill the skyward field of view. Gallery: Perseid Meteor Shower 2024 and Aurorae
Meteor Borealis
Aug. 16, 2024
A single exposure made with a camera pointed almost due north on August 12 recorded this bright Perseid meteor in the night sky west of Halifax, Nova Scotia, Canada. The meteor's incandescent trace is fleeting. It appears to cross the stars of the Big Dipper, famous northern asterism and celestial kitchen utensil, while shimmering curtains of aurora borealis, also known as the northern lights, dance in the night. Doubling the wow factor for night skywatchers near the peak of this year's Perseid meteor shower auroral activity on planet Earth was enhanced by geomagnetic storms. The intense space weather was triggered by flares from an active Sun. Gallery: Perseid Meteor Shower 2024 and Aurorae
Late Night Vallentuna
Aug. 15, 2024
Bright Mars and even brighter Jupiter are in close conjunction just above the pine trees in this post-midnight skyscape from Vallentuna, Sweden. Taken on August 12 during a geomagnetic storm, the snapshot records the glow of aurora borealis or northern lights, beaming from the left side of the frame. Of course on that date Perseid meteors rained through planet Earth's skies, grains of dust from the shower's parent, periodic comet Swift-Tuttle. The meteor streak at the upper right is a Perseid plowing through the atmosphere at about 60 kilometers per second. Also well-known in Earth's night sky, the bright Pleiades star cluster shines below the Perseid meteor streak. In Greek myth, the Pleiades were seven daughters of the astronomical titan Atlas and sea-nymph Pleione. The Pleiades and their parents' names are given to the cluster's nine brightest stars. Gallery: Perseid Meteor Shower 2024 and Aurorae
Meteors and Aurora over Germany
Aug. 14, 2024
This was an unusual night. For one thing, the night sky of August 11 and 12, earlier this week, occurred near the peak of the annual Perseid Meteor Shower. Therefore, meteors streaked across the dark night as small bits cast off from Comet Swift-Tuttle came crashing into the Earth's atmosphere. Even more unusually, for central Germany at least, the night sky glowed purple. The red-blue hue was due to aurora caused by an explosion of particles from the Sun a few days before. This auroral storm was so intense that it was seen as far south as Texas and Italy, in Earth's northern hemisphere. The featured image composite was built from 7 exposures taken over 26 minutes from Ense, Germany. The Perseids occur predictably every August, but auroras visible this far south are more unusual and less predictable. Gallery: Perseid Meteor Shower 2024 and Aurorae
Giant Jet from the International Space Station
Aug. 13, 2024
What's that on the horizon? When circling the Earth on the International Space Station early last month, astronaut Matthew Dominick saw an unusual type of lightning just beyond the Earth's edge: a gigantic jet. The powerful jet appears on the left of the featured image in red and blue. Giant jet lightning has only been known about for the past 23 years. The atmospheric jets are associated with thunderstorms and extend upwards towards Earth's ionosphere. The lower part of the frame shows the Earth at night, with Earth's thin atmosphere tinted green from airglow. City lights are visible, sometimes resolved, but usually creating diffuse white glows in intervening clouds. The top of the frame reveals distant stars in the dark night sky. The nature of gigantic jets and their possible association with other types of Transient Luminous Events (TLEs) such as blue jets and red sprites remains an active topic of research. Growing Gallery: Perseid Meteor Shower 2024 and Aurorae
Perseid Meteors over Stonehenge
Aug. 12, 2024
What's happening in the sky above Stonehenge? A meteor shower: specifically, the Perseid meteor shower. A few nights ago, after the sky darkened, many images of meteors from this year's Perseids were captured separately and merged into a single frame. Although the meteors all traveled on straight paths, these paths appear slightly curved by the wide-angle lens of the capturing camera. The meteor streaks can all be traced back to a single point on the sky called the radiant, here just off the top of the frame in the constellation of Perseus. The same camera took a deep image of the background sky that brought up the central band of our Milky Way galaxy running nearly vertical through the image center. The featured image was taken from Wiltshire, England, being careful to include, at the bottom, the famous astronomical monument of Stonehenge. Although the Perseids peaked last night, some Perseid meteors should still be visible for a few more nights.