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03/09/2020 – A NASA mission to the Trojans, strange asteroids in Jupiter’s orbit

March 9, 2020 Comments off

Ephemeris for Monday, March 9th. Today the Sun will be up for 11 hours and 36 minutes, setting at 7:41, and it will rise tomorrow at 8:03. The Moon, at full today, will rise at 7:46 this evening.

Lucy is a NASA mission (https://www.nasa.gov/content/goddard/lucy-the-first-mission-to-jupiter-s-trojans) whose name is not some tortured acronym. It is named for a Beatles tune and a hominid fossil found in Africa. It will set off in October next year to study two groups of strange asteroids, Jupiter’s Trojan asteroids. These asteroids lie in two swarms in Jupiter’s orbit averaging 60 degrees ahead and 60 degrees behind Jupiter. They congregate around two gravitational points in the Jupiter-Sun system called Lagrangian points, specifically L4 ahead of Jupiter and L5 behind. The Lucy spacecraft will put itself in such an orbit that it can loop between the Earth’s orbit and each of the two Trojan swarms passing by several of the asteroids. In general the names given to the asteroids are for the characters from Homer’s Iliad.  The L4 group named or the Greeks and the L5 group named for the Trojans. I’ll be visiting this mission and that of Trojan asteroids in the future. The Earth actually has one known Trojan asteroid.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum:

trojan asteroids of Jupiter

The inner solar system with Jupiter’s Trojan asteroids. The Hilda asteroids have orbital periods of 2/3rds Jupiter’s period.  Their elliptical orbits rise from the asteroid belt (white dots) to the L3, L4 and L5 points respectively. Credit: Mdf at English Wikipedia.

Lagrange points

The 5 Lagrange points about two bodies orbiting each other. The Lagrange or Lagrangian points of gravitational equilibrium were discovered by Joseph-Louis Lagrange (1736-1813). Credit Georgia State University.

12/13/2019 – Ephemeris – Tonight is the first night that straddles the peak of the Geminid meteor shower

December 13, 2019 Comments off

Ephemeris for Friday, December 13th. Today the Sun will be up for 8 hours and 50 minutes, setting at 5:02, and it will rise tomorrow at 8:12. The Moon, 1 day past full, will rise at 6:33 this evening.

Tonight and tomorrow nights will straddle the peak of the Geminid meteor shower. It is the best meteor shower of the year and it is getting more active over the years. The Moon will interfere with all but the brightest meteors. The radiant is the point in space where the meteors seem to come from, which is near the star Castor in the constellation Gemini from which the shower gets its name. The meteors will be seen all over the sky, but they all can be traced back to the radiant. The body responsible for this meteor shower is an asteroid rather than a comet with the name 3200 Phaethon. It comes very close to the sun, So it may shed bits of itself due to heat stress. I suppose I can’t resist this: That’s how the asteroid crumbles.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

3200 Phaethon showing a tail

3200 Phaethon a rock comet showing a tail as it nears the Sun. Credit NASA/STEREO

Eastern sky for Geminids

Eastern sky for Geminids at 10 p.m. December 13, 2019. On the 14th the Moon will be the same distance from Pollux but below it. Remember that the Geminid meteors will be seen all over the sky. It might help to hide the moon behind a building so as to better see the brighter meteors. Created using Stellarium.

The orbit of 3200 Phaethon

Orbit of 3200 Phaethon with the Earth and Phaethon at 10:02 p.m. December 12, 2019. (03:02 UT Dec 13) Credit TheSkyLive.com.

Geminid Orbits

Orbits of Fireballs on the night of December 13-14 as recorded by NASA’s All Sky Cameras six years ago. The preponderance of fireballs (bright meteors) are Geminids. These are published daily on Spaceweather.com. Credit: NASA and Spaceweather.com.

Eastern sky for Geminids

Eastern sky for Geminids at 10 p.m. December 13, 2019. On the 14th the Moon will be the same distance from Pollux but below it. Remember that the Geminid meteors will be seen all over the sky. It might help to hide the moon behind a building so as to better see the brighter meteors. Created using Stellarium.

From the International Meteor Organization: Observing proposal: Geminids and Full Moon

 

11/05/2019 – Ephemeris – Is the asteroid Hygiea the smallest dwarf planet?

November 5, 2019 Comments off

Ephemeris for Election Day in some places, Tuesday, November 5th. Today the Sun will be up for 10 hours even, setting at 5:26, and it will rise tomorrow at 7:27. The Moon, 1 day past first quarter, will set at 1:12 tomorrow morning.

The asteroid Hygiea is the 4th largest asteroid in the asteroid belt between Mars and Jupiter. After much study with the European Southern Observatory’s Very Large Telescope (VLT) it appears that Hygiea is very nearly spherical. Only the largest asteroid and dwarf planet Ceres is more spherical, and it’s over twice as large. Ceres is 587 miles (945 km) in diameter. Hygiea is 267 miles (430 km) in diameter. By current definition that a body not fitting the definition of planet because it hadn’t cleared it’d orbit of other objects could have the classification of dwarf planet of it was round, or in astronomer-speak has achieved hydrostatic equilibrium. If the International Astronomical Union agrees it would be the smallest dwarf planet.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

SPHERE image of Hygiea

A new SPHERE/VLT image of Hygiea, which could be the Solar System’s smallest dwarf planet yet. As an object in the main asteroid belt, Hygiea satisfies right away three of the four requirements to be classified as a dwarf planet: it orbits around the Sun, it is not a moon and, unlike a planet, it has not cleared the neighbourhood around its orbit. The final requirement is that it have enough mass that its own gravity pulls it into a roughly spherical shape. This is what VLT observations have now revealed about Hygiea.

For more from Universe Today: https://www.universetoday.com/143897/asteroid-hygiea-is-round-enough-that-it-could-qualify-as-a-dwarf-planet-the-smallest-in-the-solar-system/.

09/12/2019 – Ephemeris – NASA and the Europeans plan to deflect an asteroid

September 12, 2019 Comments off

Ephemeris for Thursday, September 12th. Today the Sun will be up for 12 hours and 41 minutes, setting at 7:59, and it will rise tomorrow at 7:19. The Moon, 2 days before full, will set at 6:30 tomorrow morning.

Meeting now in Rome is the AIDA International Conference. It has nothing to do with the opera, but a tortured acronym for Asteroid Impact Deflection Assessment. NASA and the European Space Agency are going to target the satellite of a binary near Earth asteroid Didymos. NASA will supply DART, the impactor, The Italians, a cube sat to fly along and record the impact. Later the Europeans will launch a probe to assess the asteroid deflection. Didymos itself is a half mile in diameter (2560 ft, 780 m), its satellite, a bit more than 500 feet (525 ft, 160 m). The impact should make a marked change in the small body’s orbit of its parent. DART’s launch should come in the summer of 2021 with impact in 2022.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

DART Mission

Schematic of the DART mission shows the impact on the moonlet of asteroid (65803) Didymos. Post-impact observations from Earth-based optical telescopes and planetary radar would, in turn, measure the change in the moonlet’s orbit about the parent body. Credits and caption: NASA/Johns Hopkins Applied Physics Lab.

More information: https://www.universetoday.com/143313/europe-and-us-are-going-to-try-and-deflect-an-asteroid/

https://www.nasa.gov/planetarydefense/dart

11/15/2018 – Ephemeris – Last year’s interstellar visitor was acting funny

November 15, 2018 Comments off

Ephemeris for Thursday, November 15th. The Sun will rise at 7:39. It’ll be up for 9 hours and 34 minutes, setting at 5:14. The Moon, at first quarter today, will set at 12:18 tomorrow morning.

Last year about this time a fast moving asteroid with an odd cigar shape passed through the inner solar system. It’s velocity was such that it didn’t come from around here, meaning our solar system. It was named ‘Oumuamua by its discoverers in Hawai’i. It was spotted as it was heading out, away from the Sun. As it does so, it decelerates as the Sun’s gravitational pull tries to pull it back in. After studying its motion, astronomers noticed that it wasn’t decelerating as fast as it should if it was on a simple ballistic trajectory. Something about it was accelerating it, or causing it to not decelerate as fast as it should. Despite rampant speculation that it’s an interstellar craft on social media ‘Omuamua’s acceleration is well within that possible for comets.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

'Oumuamua
Artist visualization of ‘Oumuamua. Credit: European Southern Observatory / M. Kornmesser
Orbit of 'Oumuamua
Orbit of ‘Oumuamua 1I/2017 U1. Uncredited image from Ars Technica.

10/15/2018 – Ephemeris – The Japanese spacecraft Hayabusa2 is exploring the asteroid Ryugu.

October 15, 2018 Comments off

Ephemeris for Monday, October 15th. The Sun will rise at 7:58. It’ll be up for 11 hours even, setting at 6:58. The Moon, 1 day before first quarter, will set at 11:43 this evening.

The Japanese asteroid sample return mission Hayabusa2 is in the midst of operations at the near-earth asteroid Ryugu. It dropped three rovers that hopped across its surface and later this month will take the first of three samples. Hayabusa means peregrine falcon in Japanese. It will stay at the asteroid until late next year, it then will make a year-long trip back to the Earth, landing in the Outback of Australia. NASA’s own OSIRIS-REx asteroid sample return mission is currently approaching the near-earth asteroid Bennu. It will orbit the asteroid for over a year and can make up to three attempts to take a sample of the asteroid for return to Earth. It is to land at the Utah Test and Training Range in September of 2023.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Hayabusa2 dropping a rover onto Ryugu
An artist’s rendering of Hayabusa2 dropping a rover onto Ryugu. Credit: JAXA/Akihiro Ikeshita.
Ryugu surface
A Hayabusa2 rover captured the surface of Ryugu mid-hop. Credit: JAXA.
OSIRIS-REx at Bennu
Artist’s view of OSIRIS-REx attempting to get a sample from Bennu. Credit: NASA.

11/02/2017 – Ephemeris – Interstellar asteroid discovered passing through the solar system

November 2, 2017 1 comment

Ephemeris for Thursday, November 2nd. The Sun will rise at 8:21. It’ll be up for 10 hours and 7 minutes, setting at 6:29. The Moon, 2 days before full, will set at 7:21 tomorrow morning.

Apparently an interloper has entered the solar system. No, it’s not Nibiru, unless Nibiru is only 525 feet (160 meters) across. It’s name, for now, is A/2017 U1. It’s official name, when it gets one, will be given to this new class of asteroids.. It’s on a hyperbolic trajectory, meaning it won’t be back. We know there are rogue planets, kicked out of their star systems, so why not asteroids and comets? It had an interstellar space velocity relative to the Sun of 15.8 miles per second (25.5 km/s) coming from the direction of the constellation of Lyra. Interestingly that’s the direction the Sun is traveling toward relative to our neighboring stars at nearly the same speed. Maybe it didn’t so much as to run into us, but the Sun and our solar system ran into it!

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

A/2017 U1

Asteroid A/2017 U1 orbit animation. Click to enlarge. Credit NASA/JPL-Caltech.

This body was discovered because it came close to the Earth.  There are probably many of them passing through the solar system  that never come close enough to be found.

Here’s a link: https://www.nasa.gov/feature/jpl/small-asteroid-or-comet-visits-from-beyond-the-solar-system