Merkur ist der erste Planet im Sonnensystem. Er ist nicht besonders leicht zu beobachten, da er am Himmel immer dicht bei der Sonne steht. Selbst in der. umum.nu hat aktuelle Nachrichten aus den Bereichen: Politik, Berlin, Deutschland, Wahl, Ausland, bayerischer Landtag, CSU, München, Seehofer, FDP. Merkur (Eigenschreibweise: MERKUR) ist eine österreichische Verbrauchermarktkette, die zur deutschen Rewe International AG gehört.
The first telescopic observations of Mercury were made by Galileo in the early 17th century. Although he observed phases when he looked at Venus, his telescope was not powerful enough to see the phases of Mercury.
In , Pierre Gassendi made the first telescopic observations of the transit of a planet across the Sun when he saw a transit of Mercury predicted by Johannes Kepler.
In , Giovanni Zupi used a telescope to discover that the planet had orbital phases similar to Venus and the Moon. The observation demonstrated conclusively that Mercury orbited around the Sun.
A rare event in astronomy is the passage of one planet in front of another occultation , as seen from Earth.
Mercury and Venus occult each other every few centuries, and the event of May 28, is the only one historically observed, having been seen by John Bevis at the Royal Greenwich Observatory.
The difficulties inherent in observing Mercury mean that it has been far less studied than the other planets. The effort to map the surface of Mercury was continued by Eugenios Antoniadi , who published a book in that included both maps and his own observations.
In June , Soviet scientists at the Institute of Radio-engineering and Electronics of the USSR Academy of Sciences , led by Vladimir Kotelnikov , became the first to bounce a radar signal off Mercury and receive it, starting radar observations of the planet.
Dyce, using the meter Arecibo Observatory radio telescope in Puerto Rico , showed conclusively that the planet's rotational period was about 59 days.
If Mercury were tidally locked, its dark face would be extremely cold, but measurements of radio emission revealed that it was much hotter than expected.
Astronomers were reluctant to drop the synchronous rotation theory and proposed alternative mechanisms such as powerful heat-distributing winds to explain the observations.
Italian astronomer Giuseppe Colombo noted that the rotation value was about two-thirds of Mercury's orbital period, and proposed that the planet's orbital and rotational periods were locked into a 3: Instead, the astronomers saw the same features during every second orbit and recorded them, but disregarded those seen in the meantime, when Mercury's other face was toward the Sun, because the orbital geometry meant that these observations were made under poor viewing conditions.
Ground-based optical observations did not shed much further light on Mercury, but radio astronomers using interferometry at microwave wavelengths, a technique that enables removal of the solar radiation, were able to discern physical and chemical characteristics of the subsurface layers to a depth of several meters.
Moreover, recent technological advances have led to improved ground-based observations. In , high-resolution lucky imaging observations were conducted by the Mount Wilson Observatory 1.
They provided the first views that resolved surface features on the parts of Mercury that were not imaged in the Mariner 10 mission.
Reaching Mercury from Earth poses significant technical challenges, because it orbits so much closer to the Sun than Earth.
Therefore, the spacecraft must make a large change in velocity delta-v to enter a Hohmann transfer orbit that passes near Mercury, as compared to the delta-v required for other planetary missions.
The potential energy liberated by moving down the Sun's potential well becomes kinetic energy ; requiring another large delta-v change to do anything other than rapidly pass by Mercury.
To land safely or enter a stable orbit the spacecraft would rely entirely on rocket motors. Aerobraking is ruled out because Mercury has a negligible atmosphere.
A trip to Mercury requires more rocket fuel than that required to escape the Solar System completely. As a result, only two space probes have visited it so far.
The second close approach was primarily used for imaging, but at the third approach, extensive magnetic data were obtained. The data revealed that the planet's magnetic field is much like Earth's, which deflects the solar wind around the planet.
For many years after the Mariner 10 encounters, the origin of Mercury's magnetic field remained the subject of several competing theories. On March 24, , just eight days after its final close approach, Mariner 10 ran out of fuel.
Because its orbit could no longer be accurately controlled, mission controllers instructed the probe to shut down. It made a fly-by of Earth in August , and of Venus in October and June to place it onto the correct trajectory to reach an orbit around Mercury.
The probe successfully entered an elliptical orbit around the planet on March 18, The first orbital image of Mercury was obtained on March 29, The probe finished a one-year mapping mission,  and then entered a one-year extended mission into The mission was designed to clear up six key issues: Mercury's high density, its geological history, the nature of its magnetic field , the structure of its core, whether it has ice at its poles, and where its tenuous atmosphere comes from.
To this end, the probe carried imaging devices that gathered much-higher-resolution images of much more of Mercury than Mariner 10 , assorted spectrometers to determine abundances of elements in the crust, and magnetometers and devices to measure velocities of charged particles.
Measurements of changes in the probe's orbital velocity were expected to be used to infer details of the planet's interior structure.
Both probes will operate for one terrestrial year. From Wikipedia, the free encyclopedia. For other uses, see Mercury disambiguation.
Smallest and closest planet to the Sun in the Solar System. Moment of inertia factor. The so-called "Weird Terrain" formed at the point antipodal to the Caloris Basin impact.
Animation of Mercury's and Earth's revolution around the Sun. Perihelion precession of Mercury. Size comparison with other Solar System objects.
Mercury, Venus , Earth , Mars. Mars , Mercury Front: Moon , Pluto , Haumea. Pluto's orbital eccentricity is greater than Mercury's.
Pluto is also smaller than Mercury, but was thought to be larger until The "4" is a reference number in the Sumero-Akkadian transliteration system to designate which of several syllables a certain cuneiform sign is most likely designating.
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Translated from French by Moore, Patrick. The symbol for Mercury represents the Caduceus, a wand with two serpents twined around it, which was carried by the messenger of the gods.
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Radar images of the equatorial and midlatitude zones". Retrieved June 10, Archived from the original on July 21, Retrieved June 18, Like the Sierra, the Scorpio was also introduced to replace another popular model, the Ford Granada.
In the UK and Ireland, the Granada name was still used, with the Scorpio name reserved for the top of the range Granada models.
The Scorpio started as a five-door hatchback, and it later became available as a four-door sedan and a five-door wagon.
An "executive express" in the form of the Scorpio Cosworth was produced, powered by a 2. This featured 16" aluminum alloy wheels similar to the AMG Mercedes wheels, a rear spoiler, and additional ground effects.
On average, each Lincoln-Mercury dealer sold one to two Merkur vehicles. Several factors led to the slow sales of the Merkur line, including an unfavorable exchange rate between the dollar and the West German Deutsche mark , leading to unstable pricing.
By , the Merkur Scorpio rivaled the Lincoln Town Car in price, despite its strong visual resemblance to the far more affordable Mercury Sable both sold on the same showroom floor.
At the end of , the decision to drop the Merkur line was driven by future passive restraint requirements in North America.
To bring the XR4Ti and Scorpio into compliance, the model lines would have needed airbag s or a passive restraint system automatic seatbelts to do so.
As the slow sales of the model line no longer justified the expense of such a redesign their European counterparts would not receive airbags until they were replaced in , Ford chose to end the Merkur line, withdrawing the XR4Ti in early with the Scorpio following at the end of the model year.
The name represents the crew that looked and seemed awesome, but "completely fell apart and the dashboard lit up like a Christmas tree at 15, miles.
Right after the warranty expired. From Wikipedia, the free encyclopedia. For other uses, see Merkur disambiguation. Not to be confused with Mercury automobile.
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