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Jupiter May Help Supercharge Orionid Meteor Shower | Halley's Comet | Space.com - 0 views

www.space.com/met-orionid-meteor-shower.html

scibyte40 comet jupiter Halley

shared by Mars Base on 28 Mar 12 - No Cached
  • Jupiter's powerful gravity can help supercharge a meteor shower caused by trailing chunks of the famed Halley's comet, a new study suggests
  • Every October, skywatchers are treated to a dazzling show when the Orionid meteors — leftover bits of Halley's comet
  • The Orionids are incredibly active from time to
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  • activity is generated by a complex orbital interplay among Jupiter, the comet and the meteoroids
  • according to the study
  • Previous research had suggested that intense Orionid outbursts occur after the meteoroids fall into resonances with Jupiter's orbit
  • Resonances are gravitational sweet spots in which objects' orbits around the sun are related by a ratio of two whole numbers. (A 1:2 resonance, for example, means that one body completes one orbit in the time it takes another object to make two orbits.)
  • new study finds that Halley's comet itself has likely been in resonances with Jupiter in the
  • which in turn increases the odds of populating the Orionid stream with resonant meteoroids
  • particles ejected during those times tend to clump together due to periodic effects from Jupiter
  • modeled the orbital evolution of Halley's comet over a long stretch of time
  • from more than 12,000 years in the past to 15,000 years into the future
  • determind that from 1404 B.C. to 690 B.C., the comet was likely trapped in a 1:6 resonance with Jupiter
  • Halley completed one orbit for every six orbits of Jupiter around the sun).
  • from 240 B.C. to 1700 A.D., the comet was in a 2:13 orbital resonance with Jupiter
  • Debris deposited during these two periods are directly linked to heightened activity in the Orionid meteor showers in some years, according to the study.
  • the unusual Orionid outburst observed in 1993 was due to 2:13 resonant meteoroids sloughed by Halley around 240 B.C
  • predicts that the next similarly heightened display of meteors from this 2:13 resonance will be in 2070 A.D.
Mars Base

International Cometary Explorer - Wikipedia, the free encyclopedia - 0 views

en.wikipedia.org/...nternational_Cometary_Explorer

scibyte132 ISEE-3

shared by Mars Base on 25 May 14 - No Cached
  • Original mission: International Sun/Earth Explorer 3 (ISEE-3)
  • to investigate solar-terrestrial relationships at the outermost boundaries of the Earth's magnetosphere
  • to examine in detail the structure of the solar wind near the Earth and the shock wave that forms the interface between the solar wind and Earth's magnetosphere
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  • investigate motions of and mechanisms operating in the plasma sheets
  • continue the investigation of cosmic rays and solar flare emissions in the interplanetary region near 1 AU
  • Second mission: International Cometary Explorer
  • On June 10, 1982, after completing its original mission, ISEE-3 was repurposed. It was renamed the International Cometary Explorer (ICE)
  • The primary scientific objective of ICE was to study the interaction between the solar wind and a cometary atmosphere
  • a series of lunar orbits over the next 15 months. Its last and closest pass over the Moon, on December 22, 1983, was a mere 119.4 km above the Moon's surface. By the beginning of 1984, ICE was in heliocentric orbit
  • Giacobini-Zinner encounter
  • on a trajectory intercepting that of Comet Giacobini-Zinner.
  • On 11 September 1985, the craft passed through the plasma tail of Comet Giacobini-Zinner
  • ICE carried no cameras. It instead carried instruments for measurements of energetic particles, waves, plasmas, and fields
  • Halley encounter
  • transited between the Sun and Comet Halley in late March 1986, when other spacecraft
  • were in the vicinity of Comet Halley
  • ICE flew through the tail
  • Heliospheric mission
  • mission was approved by NASA in 1991
  • consisting of investigations of coronal mass ejections in coordination with ground-based observations
  • End of mission
  • On May 5, 1997, NASA ended the ICE mission, and ordered the probe shut down, with only a carrier signal left operating
  • Further contact
  • In 1999, NASA made brief contact with ICE to verify its carrier signal. On September 18, 2008
  • NASA, with the help of KinetX, located ICE using the Deep Space Network after discovering that it had not been powered off after the 1999 contact
  • status check revealed that all but one of its 13 experiments were still functioning, and it still has enough propellant
  • Reboot effort
  • A team webpage said, "We intend to contact the ISEE-3 (International Sun-Earth Explorer) spacecraft, command it to fire its engine and enter an orbit near Earth, and then resume its original mission...If we are successful we intend to facilitate the sharing and interpretation of all of the new data ISEE-3 sends back via crowd sourcing."
  • Sometime after NASA's interest in the ICE waned
  • A team of engineers, programmers, and scientists
  • realized that the spacecraft might be steered to pass close to another comet
  • began to study the feasibility and challenges involved
  • On May 15, 2014, the project reached its crowdfunding goal
  • which will cover the costs of writing the software to communicate with the probe, searching through the NASA archives for the information needed to control the spacecraft, and buying time on the dish antennas
  • The project then set a 'stretch' goal of $150,000
  • The project members are working on deadline: if they get the spacecraft to change its orbit by late May or early June 2014, it can use the Moon's gravity to get back into a useful halo orbit.
  • Earlier in 2014, officials with the Goddard Space Flight Center had said that the Deep Space Network equipment necessary to transmit signals to the spacecraft had been decommissioned in 1999, and that replacing it was not economically feasible
  • oject members obtained the needed hardware (power amplifier, modulator/demodulator[12]), and installed it on the 305-meter Arecibo dish antenna on May 19, 2014
  • Although NASA is not funding the project, it made advisors available and gave approval to try to establish contact
  • On May 21, 2014, NASA announced that it had signed a Non-Reimbursable Space Act Agreement with the ISEE-3 Reboot Project
  • "This is the first time NASA has worked such an agreement for use of a spacecraft the agency is no longer using or ever planned to use again," officials said
Mars Base

Jupiter helps Halley's Comet give us more spectacular meteor displays - 0 views

www.physorg.com/...-comet-spectacular-meteor.html

scibyte40 jupiter comet Halley

shared by Mars Base on 28 Mar 12 - No Cached
  • The dramatic appearance of Halley's comet in the night sky has been observed and recorded by astronomers since 240 BC. Now a study shows that the orbital influences of Jupiter on the comet and the debris it leaves in its wake are responsible for periodic outbursts of activity in the Orionid meteor showers. The results will be presented by Aswin Sekhar at the National Astronomy Meeting in Manchester on Tuesday 27th March.
Mars Base

NASA - 2004 and 2012 Transits of Venus - 0 views

eclipse.gsfc.nasa.gov/...venus0412.html

scibyte38 Venus transit

shared by Mars Base on 14 Mar 12 - No Cached
  • Transits of Venus across the disk of the Sun are among the rarest of planetary alignments
  • only six such events have occurred since the invention of the telescope (1631, 1639, 1761, 1769, 1874 and 1882
  • event begins with contact I which is the instant when the planet's disk is externally tangent with the Sun. The entire disk of the Venus is first seen at contact II when the planet is internally tangent with the Sun. During the next several hours, Venus gradually traverses the solar disk at a relative angular rate of approximately 4 arc-min/hr. At contact III, the planet reaches the opposite limb and is once again internally tangent with the Sun. The transit ends at contact IV when the planet's limb is externally tangent to the Sun
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  • Geographic Visibility of 2012 June 06
  • The entire transit (all four contacts) is visible from northwestern North America, Hawaii, the western Pacific, northern Asia, Japan, Korea, eastern China, Philippines, eastern Australia, and New Zealand.
  • Sun sets while the transit is still in progress from most of North America, the Caribbean, and northwest South America
  • transit is already in progress at sunrise for observers in central Asia, the Middle East, Europe, and eastern Africa
  • No portion of the transit will be visible from Portugal or southern Spain, western Africa, and the southeastern 2/3 of South America.
  • due to the International Date Line the Western Hemisphere will see the transit on June 5.
  • Transits of Venus are only possible during early December and early June when Venus's orbital nodes pass across the Sun
  • Transits show a clear pattern of recurrence at intervals of 8, 121.5, 8 and 105.5 years
  • next pair of Venus transits occur over a century from now on 2117 Dec 11 and 2125 Dec 08.
  • Edmund Halley first realized that transits of Venus could be used to measure the Sun's distance
  • establishing the absolute scale of the solar system from Kepler's third law
  • his method proved impractical since contact timings of the desired accuracy are impossible due to the effects of atmospheric seeing and diffraction
  • the 1761 and 1769 expeditions to observe the transits of Venus gave astronomers their first good value for the Sun's distance.
  • Mercury can also transit the Sun
  • undergoes transits much more frequently. There are about 13 or 14 transits of Mercury each century
  • Mercury transits fall within several days of 8 May and 10 November
Mars Base

Asteroid 2013 UQ4 Suddenly Becomes a Dark Comet with a Bright Future - 0 views

www.universetoday.com/...ark-comet-with-a-bright-future

scibyte130

shared by Mars Base on 09 May 14 - No Cached
  • On October 23, 2013,  astronomers with the Catalina Sky Survey picked up a very faint asteroid with an unusual orbit more like a that of a comet than an asteroid
  •  At the time 2013 UQ4 was little  more than a stellar point with no evidence of a hazy coma or tail that would tag it as a comet
  • On May 7,
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  • remote telescope located in Siding Spring, Australia to take photos of 2013 UQ4 shortly before dawn in the constellation Cetus.
  • The asteroid had grown a little fuzz, making the move to comethood
  • now displays a substantial coma or atmosphere
  • . No tail is visible yet
  • it’s still bright enough to see in a 12-inch telescope under dark skie
  • Assuming the now renamed C/2013 UQ4 continues to spout dust and water vapor, it should brighten to magnitude +11 by month’s end as it moves northward across Pisces and into a dark morning sky
  • Perihelion occurs on June 5 with the comet reaching magnitude +8-9 by month’s end
  • Peak brightness of 7th magnitude is expected during its close approach of Earth on July 10 at 29 million miles (46.7 million km).
  • should be a great summer comet, plainly visible in binoculars from a dark sky
  • at the rate of some 7 degrees per night! That’s 1/3 of a degree per hour or fast enough to see movement through a telescope in a matter of minutes when the comet is nearest Earth
  • belongs to a special category of asteroids called damocloids
  • that have orbits resembling the Halley-family comets with long periods, fairly steep inclinations and highly eccentric orbits (elongated shapes)
  • Damocloids are thought to be comets that have lost all their fizz.
  • their volatile ices spent from previous trips around the sun, they stop growing comas and tails and appear identical to asteroids
  • Occasionally, one comes back to life. It’s happened in at least four other cases and appears to be happening with C/2013 UQ4 as well.
  • Studies of the comet/asteroid’s light indicate that
  • is a very dark but rather large object some 4-9 miles (7-15 km) across.
  • It’s estimated that
  • takes at least 500 years to make one spin around the sun
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