What lies at the center of our galaxy? In Jules Verne’s classic science fiction novel, A Journey to the Center of the Earth, Professor Liedenbrock and his fellow explorers encounter many strange and exciting wonders. Astronomers are already aware of some of the bizarre objects that exist at our Galactic Center, including vast cosmic dust clouds, bright star clusters, swirling gas rings, and even a supermassive black hole. Much of the Galactic Center is hidden from our view in visible light by intervening dust and gas, but it can be explored using other forms of electromagnetic radiation. The featured video is actually a digital zoom into the center of the Milky Way, beginning with visible-light images from the Digitized Sky Survey. As the movie progresses, the light shown shifts to dust-penetrating infrared, highlighting gas clouds recently discovered in 2013 that are falling toward the central black hole.
Journey to the Center of the Galaxy
Interplanetary Earth
On July 19, 2013, Earth was photographed from two other planets in the Solar System: the innermost planet, Mercury, and the ringed gas giant, Saturn. This was the first time that an interplanetary photograph of Earth was taken on the same day. The image on the left depicts Earth as a pale blue dot situated just below the rings of Saturn. This image was captured by the robotic Cassini spacecraft, which was then orbiting the outermost gas giant. On that same day, individuals across the globe captured numerous images of Saturn. On the right, the Earth-Moon system is observed against the dark background of space as captured by the sunward MESSENGER spacecraft, which was then in Mercury orbit. MESSENGER captured the image as part of a search for small natural satellites of Mercury, moons that would be expected to be quite dim. In the MESSENGER image, the brighter Earth and Moon are both overexposed and shine brightly with reflected sunlight. Both Cassini and MESSENGER have since retired from their missions of Solar System exploration, having fulfilled their intended purpose.
The Medusa Nebula
The nebula’s popular name, “The Medusa Nebula,” is derived from the braided and serpentine filaments of glowing gas observed in its structure. Additionally, this nebula is designated as Abell 21 and is classified as an old planetary nebula, situated at a distance of approximately 1,500 light-years within the Gemini constellation. Similarly to its mythological namesake, the nebula is associated with a dramatic transformation. The planetary nebula phase represents the final stage of evolution for low-mass stars like the Sun, marking their transformation from red giants to hot white dwarf stars and the subsequent shedding of their outer layers. Ultraviolet radiation from the hot star powers the nebular glow. The Medusa’s transforming star is the faint one near the center of the overall bright crescent shape. In this deep telescopic view, fainter filaments clearly extend below and to the left. The estimated diameter of the Medusa Nebula is over four light-years.
Stars and Dust in the Pacman Nebula
Stars are capable of creating extensive and complex dust structures from the dense and opaque molecular clouds from which they originate. The tools employed by stars to create their intricate structures are high-energy light and fast stellar winds. The heat generated by the stars causes the dark molecular dust to evaporate and also disperses and causes the ambient hydrogen gas to glow. The image depicts a nascent open cluster of stars, designated IC 1590, encircling the intricate interstellar dust structures within the emission nebula NGC 281. This nebula has been informally dubbed the “Pac-Man Nebula” due to its distinctive overall shape. The dust cloud situated just above the center of the image is classified as a Bok Globule, which may gravitationally collapse and form a star or stars. The Pacman Nebula is situated approximately 10,000 light-years away, within the constellation of Cassiopeia.
Helping Hand in Cassiopeia
These dusty molecular clouds, situated in the vicinity of the Milky Way galaxy, appear to extend a cosmic helping hand. These interstellar clouds are part of a local complex of star-forming interstellar clouds, which include LDN 1358, 1357, and 1355 from the 1962 Catalog of Dark Nebulae, as compiled by American astronomer Beverly Lynds. The obscuring dark nebulae, which present a challenging target for astro-imagers, are situated at a distance of approximately 3,000 light-years from Earth. They are located towards rich star fields in the northern constellation Cassiopeia. At that distance, this deep, telescopic field of view would span approximately 80 light-years.
The Milky Way galaxy over Easter Island
What was the purpose of the construction of the statues on Easter Island? The precise reason for their construction remains uncertain. It is certain that over 900 large stone statues, collectively known as moai, exist on Easter Island. The average height of a Rapa Nui (Easter Island) moai is approximately 20 meters, which is over twice the average height of a person. Additionally, the average mass of a moai is over 200 times greater than that of an average person. It is hypothesized that the anomalous statues were constructed approximately 600 years ago in the likeness of local leaders of a flourishing and archaic civilization. Rapa Nui has been designated a World Heritage Site by UNESCO. The accompanying illustration depicts some of the stone colossi imaged last month under the central band of our Milky Way galaxy. The discovery of previously unknown moais persists.
The planet Saturn at night
Saturn is a prominent object in Earth’s nocturnal sky. The telescopic view of the outer gas giant planet and its beautiful rings frequently renders it a prominent subject at star parties. However, this impressive view of Saturn’s rings and night side is not accessible through telescopes in the vicinity of planet Earth. From the inner Solar System, the view is limited to Saturn’s daytime side. This image of Saturn’s slender crescent illuminated by sunlight and its extensive, intricate ring system in shadow was captured by the Cassini spacecraft. Launched from Earth, the robotic Cassini spent 13 years in Saturn’s orbit before being directed to enter the gas giant’s atmosphere on September 15, 2017.
The South Pacific Shadowset
The full moon and Earth’s shadow are depicted together in this island skyscape. The captivating spectacle was observed and documented on Tuesday morning, August 20, from Fiji, located in the South Pacific Ocean. For those who rise early, the shadow in the western sky is a daily phenomenon. Nevertheless, the gray-blue shadow is frequently disregarded in favor of a more luminous eastern horizon. The Earth’s setting shadow extends through the dense atmosphere and is bounded above by a pinkish glow, which is referred to as the anti-twilight arch. The arch is known as the Belt of Venus, and its distinctive hue is the result of backscattering of reddened light from the opposite horizon’s rising Sun. It should be noted that the light of the setting Moon is reddened by the long sightline through the atmosphere. However, on the aforementioned date, the full Moon could be designated a seasonal Blue Moon, representing the third full Moon in a season with four full Moons. Furthermore, while the full Moon is always impressive near the horizon, August’s full Moon is regarded by some as the first of four consecutive full Supermoons in 2024.
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M31, also known as the Andromeda Galaxy
The most distant object readily visible without the aid of optical instruments is M31, also known as the Great Andromeda Galaxy. Despite its distance of approximately two and a half million light-years, this vast spiral galaxy, spanning over 200,000 light-years, can be observed as a faint and nebulous cloud in the constellation Andromeda. The image depicts a bright yellow nucleus, dark winding dust lanes, and expansive spiral arms, which are dotted with blue star clusters and red nebulae. This stunning telescopic image combines data from the Hubble Space Telescope with ground-based images from the Subaru and Mayall telescopes. In approximately five billion years, the Andromeda galaxy may become visible to the naked eye, spanning the entire night sky, just before it merges with or passes by our Milky Way Galaxy.
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The Horsehead and Orion Nebulas
The dark Horsehead Nebula and the glowing Orion Nebula represent contrasting cosmic vistas. Situated at a distance of 1,500 light-years, these nebulae are located within one of the most recognizable constellations in the night sky. They are positioned in opposite corners of the above mosaic, which presents a stunning visual representation. The Horsehead Nebula, a well-known astronomical object, is depicted as a dark cloud with a small silhouette, outlined against the extended glow of hydrogen, represented in gold at the lower left. Alnitak is the easternmost star in Orion’s Belt and is observed as a luminous star situated to the left of the Horsehead Nebula. Immediately below Alnitak is the Flame Nebula, which exhibits bright emission clouds and dramatic dark dust lanes. The Orion Nebula (also known as M42), a magnificent emission region, is situated in the upper right quadrant. To its left is a prominent reflection nebula, which is sometimes referred to as the Running Man. Pervasive tendrils of glowing hydrogen gas can be readily discerned throughout the region.
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