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Posts Tagged ‘Origins’

08/02/2022 – Ephemeris – Where did the Moon’s “seas” come from?

August 2, 2022 Comments off

This is Ephemeris for Tuesday, August 2nd. Today the Sun will be up for 14 hours and 37 minutes, setting at 9:07, and it will rise tomorrow at 6:31. The Moon, 3 days before first quarter, will set at 11:37 this evening.

As the days progress to full moon on the 13th, the Moon will reveal its many maria or seas, as the first telescopic astronomers called these blemishes. Many have roughly circular outlines bounded by mountains. They have flat floors that are darker than the heavily cratered parts of the moon, and have very few craters on them. That means they were created after the major craters were made, and obliterated the craters beneath. The majority of the cratering came very early, as the Moon accreted from the material the was produced when a Mars sized protoplanet hit the early Earth about 4.51 billion years ago. That’s according to most planetary scientists. The maria are actually huge craters produced by large asteroids later, about 3.9 billion years ago.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). They may be different for your location.

Addendum

Tonights Moon with labels

Lunar “seas” seen on a first quarter moon. Mare is Latin for sea. Sinus means bay. Created using Stellarium, GIMP and LibreOffice.

Last quarter moon with labels

Lunar “seas” and some other prominent features labeled on the last quarter moon.

02/26/2021 – Ephemeris – Origin of the Moon

February 26, 2021 Comments off

This is Ephemeris for Friday, February 26th. Today the Sun will be up for 11 hours and 1 minute, setting at 6:26, and it will rise tomorrow at 7:23. The Moon, 1 day before full, will set at 7:59 tomorrow morning.

The origin of the Moon is a question that has vexed astronomers for years. Did it break off the molten Earth like a cell dividing? Was it captured by passing too close to the Earth? Neither is satisfactory. Chemical elements have different isotopes depending on the number of neutrons in their nucleus. The rocks brought back by the Apollo astronauts show that the isotopes of the elements in the rocks are the same as for the Earth. We know that Mars and the asteroids have different isotope ratios. The hypothesis that seems most likely is that another planet, the size of Mars collided with the 100 million-year-old Earth in a glancing blow that gave rise to a disk of material that eventually coalesced to form the Moon.

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

Addendum

How the Moon may have formed

A progression of how the Moon may have formed by a small protoplanet crashed into the Earth. Credit: Brian Koberlein.

10/19/2015 – Ephemeris – Where did the Moon come from?

October 19, 2015 Comments off

Ephemeris for Monday, October 19th.  The Sun will rise at 8:03.  It’ll be up for 10 hours and 48 minutes, setting at 6:51.   The Moon, 1 day before first quarter, will set at 11:51 this evening.

Only two planets in the solar system have moons at least a quarter the size of the planet they orbit:  The Earth and Pluto.  The Moon is a bit more than a quarter the Earths diameter while Pluto’s moon Charon is half its size.  Probably in the early days of the solar system, some four and a half billion years ago collisions were rather common.  It is thought by many planetary scientists that a Mars sized protoplanet collided with the proto-earth with a glancing blow to rip off much of the Earth’s crust, thrust it into orbit where it coalesced into the Moon.  It seems that Pluto’s Charon may have been formed much the same way.  Some thing the varying axial tilts of the planets may have been caused the same way by smaller objects.

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

Addendum

Collision spawning the Moon

The hypothetical collision of a Mars sized body with the young Earth. Credit: Joe Tucciarone via NASA

Breaking News

Robert Farquhar the man behind the ISEE-3 spacecraft, the first to hang out at the Earth-Sun L1 point between the Earth and the Sun back in 1978 passed away yesterday.  In 1982 he “stole” the spacecraft and through an amazing number of maneuvers using very little fuel managed to send it through the tail of Comet Gicobini-Zinner ahead of the fleet of spacecraft then aimed at Halley’s Comet.  Last year when the then renamed spacecraft ICE approached the Earth, he hatched a plan to return the spacecraft to its L1 position.  Unfortunately apparently there was not enough fuel pressure to complete the burns necessary for the task.  I’ll have a program on Robert Farquhar next Monday.