Posts tagged solar system

Posted 12 months ago

Crescent Neptune and Triton 
Image Credit: Voyager 2, NASA

Explanation: Gliding silently through the outer Solar System, the Voyager 2 spacecraft camera captured Neptune and Triton together in crescent phase in 1989. The elegant picture of the gas giant planet and its cloudy moon was taken from behind just after closest approach. It could not have been taken from Earth because Neptune never shows a crescent phase to sunward Earth. The unusual vantage point also robs Neptune of its familiar blue hue, as sunlight seen from here is scattered forward, and so is reddened like thesetting SunNeptune is smaller but more massive than Uranus, has several dark rings, and emits more light than it receives from the Sun.

Posted 1 year ago

Comet PANSTARRS and the Andromeda Galaxy 
Image Credit & Copyright: Pavel Smilyk

Explanation: Currently, comet PANSTARRS is passing nearly in front of the galaxy Andromeda. Coincidentally, both comet and galaxyappear now to be just about the same angular size. In physical size, even though Comet PANSTARRS is currently the largest object in theSolar System with a tail spanning about 15 times the diameter of the Sun, it is still about 70 billion times smaller than the Andromeda galaxy(M31). The above image was captured on March 30, near SyktyvkarRussia. As C/2011 L4 (PANSTARRS) on the lower left recedesfrom the Sun and dims, it is returning to the northerly direction whence it came. When the comet will return is currently unknown, althoughhumans may have merged with computers by then.

Posted 1 year ago

Moon or Frying Pan? 
Images Credit: Frying Pan (Copyrighted): Christopher JonassenMoon: NASA

Explanation: Which is which? Of the two images shown above, one is a moon in our Solar System, while the other is the bottom of frying pan. We are not making this up — can you tell a pan from a planetoid? Think you got it? To find the answer click here. OK, but there are more! That’s right: you, your family, friends, neighbors, and local elected officials can all play “Moon or Frying Pan” with these other image pairs, too. As everyone knows, the fundamental underlying reason why moons and frying pans appear similar is — OK, we at APOD aren’t sure either. And if you’ve been fooled, don’t fret — just remember that it’s OK because today is April Fool’s Day.

Posted 1 year ago

GRAIL Maps the Moon’s Gravity 
Image Credit & Copyright: NASAJPL-CaltechMITGSFCSVC

Explanation: How did the Moon form? To help find out, NASA launched the twin Gravity Recovery and Interior Laboratory(GRAIL) satellites in 2011 to orbit and map the Moon’s surface gravity in unprecedented detailPictured above is a resultingGRAIL gravity map, with regions of slightly lighter gravity shown in blue and regions of slightly stronger gravity shown in red. Analysis of GRAIL data indicates that the moon has an unexpectedly shallow crust than runs about 40 kilometers deep, and an overall composition similar to the Earth. Although other surprising structures have been discovered that will continue to be investigated, the results generally bolster the hypothesis that the Moon formed mostly from Earth material following a tremendous collision in the early years of our Solar System, about 4.5 billion years ago. After completing their mission and running low on fuel, the two GRAIL satellites, Ebb and Flow, were crashed into a lunar crater at about 6,000 kilometer per hour.

Posted 1 year ago

Saturn’s Hexagon and Rings 
Image Credit: NASA/JPL-Caltech/Space Science Institute

Explanation: Why would clouds form a hexagon on Saturn? Nobody is sure. Originally discovered during the Voyager flybys of Saturn in the 1980s, nobody has ever seen anything like it anywhere else in the Solar System. If Saturn’s South Pole wasn’t strange enough with its rotating vortex, Saturn’s North Pole might be considered even stranger. The bizarre cloud pattern is shown above in great detail by a recent image taken by the Saturn-orbiting Cassini spacecraft. This and similar images show the stability of the hexagon even 20+ years after Voyager. Movies of Saturn’s North Pole show the cloud structure maintaining its hexagonal structure while rotating. Unlike individual clouds appearing like a hexagon on Earth, the Saturn cloud pattern appears to have six well defined sides of nearly equal length. Four Earths could fit inside the hexagon. Imaged from the side, the dark shadow of the Jovian planet is seen eclipsing part of its grand system of rings, partly visible on the upper right.

Posted 1 year ago

The Great Russian Meteor of 2013 
Video Credit & Copyright: RussiaToday

Explanation: What in heaven’s blazes is that? Thousands of people living near the Ural Mountains in Russia saw last Friday morning one of the more spectacular meteors of modern times streak across the sky. Forceful sound waves arrived at the ground minutes later, knocking people over and breaking windows for hundreds of kilometers. The above video is a compilation of several car dashcams and includes real time footage of the meteor rampaging, smoke trails drifting, shadows quickly shifting, and even the meteor’s light reflecting off the back of a bus. The fireball is thought to have been caused by a car-sized chunk of ice and rock crashing into the Earth’s atmosphere. Since the event was captured from so many angles, the meteor’s trajectory has become determined well enough to indicate from where it came and to where any resultant pieces might have landed. It is already certain that this meteor had nothing to do with the several-times larger asteroid 2012 DA14 which passed the Earth from a different direction later the same day. If pieces of the meteor are found, they might tell humanity more about the early Solar System, when the meteor was likely formed.

Posted 1 year ago

Solar System Portrait 
Image Credit: Voyager ProjectNASA

Explanation: On another Valentine’s Day (February 14, 1990), cruising four billion miles from the Sun, the Voyager 1 spacecraft looked back to make this first ever family portrait of our Solar System. The complete portrait is a 60 frame mosaic made from a vantage point 32 degrees above the ecliptic plane. In it, Voyager’s wide angle camera frames sweep through the inner Solar System at the left, linking up with gas giant Neptune, at the time the Solar System’s outermost planet, at the far right. Positions for Venus, Earth, Jupiter, Saturn, Uranus, and Neptune are indicated by letters, while the Sun is the bright spot near the center of the circle of frames. The inset frames for each of the planets are from Voyager’s narrow field camera. Unseen in the portrait are Mercury, too close to the Sun to be detected, and Mars, unfortunately hidden by sunlight scattered in the camera’s optical system. Small, faint Pluto’s position was not covered.

Posted 1 year ago

A Solar Ballet 
Video Credit: NASA/Goddard/SDO AIA Team

Explanation: Sometimes, the Sun itself seems to dance. On just this past New Year’s Eve, for example, NASA’s Sun-orbiting Solar Dynamic Observatoryspacecraft imaged an impressive prominence erupting from the Sun’s surface. The dramatic explosion was captured in ultraviolet light in the above time lapse videocovering four hours. Of particular interest is the tangled magnetic field that directs a type of solar ballet for the hot plasma as it falls back to the Sun. The scale of the disintegrating prominence is huge — the entire Earth would easily fit under the flowing curtain of hot gas. 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 still a topic ofresearch. As the Sun nears Solar Maximum this year, solar activity like eruptive prominences should be common.

Posted 1 year ago

Makemake of the Outer Solar System 
Illustration Credit: European Southern Observatory

Explanation: Makemake is one of the largest objects known in the outer Solar System. Pronounced MAH-kay MAH-kay, this Kuiper belt object is about two-thirds the size of Pluto, orbits the Sun only slightly further out than Pluto, and appears only slightly dimmer than Pluto. Makemake, however, has an orbit much more tilted to the ecliptic plane of the planets than Pluto. Discovered by a team led by Mike Brown (Caltech) in 2005, the outer Solar System orb was officially named Makemake for the creator of humanity in the Rapa Nui mythology of Easter Island. In 2008, Makemake was classified as a dwarf planet under the subcategory plutoid, making Makemake the third cataloged plutoid after Pluto and Eris. Makemake is known to be a worldsomewhat red in appearance, with colors indicating it is likely covered with patchy areas of frozen methane. No images of Makemake's surface yet exist, but an artist's illustration of the distant world is shown above. Careful monitoring of the brightness drop of a distant star recently eclipsed by Makemake indicates that the dwarf planet has little atmosphere.

Posted 1 year ago

Jupiter and Io 
Image Credit & CopyrightAlessandro Bianconi

Explanation: On December 3 (UT), Jupiter, the solar system’s largest planet, will be at opposition, opposite the Sun in planet Earth’s sky, shining brightly and rising as the Sun sets. That configuration results in Jupiter’s almost annual closest approach to planet Earth. So, near opposition the gas giant offers earthbound telescopes stunning views of its stormy, banded atmosphere and large Galilean moons. For example, this sharp series was recorded on the night of November 16/17 from the island of Sardinia near Dolianova, Italy. North is up in the images that show off Jupiter’s famous Great Red Spot, and planet girdling dark belts and light zones. Also seen in transit is Jupiter’s volcanic moon Io, its round, dark shadow tracking across the Jovian cloud tops as the sequence progresses left to right.