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Archive for the ‘Astronomical History’ Category

03/02/2020 – Ephemeris – Greek use of the first quarter Moon

March 2, 2020 Comments off

Ephemeris for Monday, March 2nd. Today the Sun will be up for 11 hours and 14 minutes, setting at 6:32, and it will rise tomorrow at 7:15. The Moon, at first quarter today, will set at 2:39 tomorrow morning.

The Moon is at first quarter at 2:57 this afternoon. The ancient Greek philosopher/astronomer Aristarchus* tried to determine the distance to the Sun by observing the Moon at exactly first quarter and measuring the angle between it and the Sun. If we see the Moon at exactly first quarter when the sunrise line called the terminator cuts the Moon exactly in half then the angle at the Moon between the Sun and the Earth is a right or 90 degree angle. If we, on the Earth at that same instant were able to measure the angular distance between the Moon and the Sun. we could theoretically calculate the distance to the Sun. He was correct about the Moon’s distance, but calculated the Sun was at only about 10% of its actual distance.

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

* In the actual broadcast program I erroneously credited the later Greek astronomer Hipparchus.

Addendum

Quarter Mon method of determining the Sun's distance

Quarter Moon method of determining the Sun’s distance by Aristarchus. Credit: andonee

12/27/2019 – Ephemeris – A Decade of astronomical and space firsts

December 27, 2019 Comments off

Ephemeris for Friday, December 27th. Today the Sun will be up for 8 hours and 49 minutes, setting at 5:08, and it will rise tomorrow at 8:19. The Moon, 1 day past new, will set at 6:38 this evening.

The 2010s were quite a decade in astronomy and space. 24 years ago the first exoplanet, that is planet orbiting another star, was discovered: 51 Pegasi b. As of December 8th the number of confirmed exoplanets stands at 4,104. At mid decade we got a close look at the dwarf planet Pluto and its moons, and early this year at the distant object temporarily called Ultima Thule. Early this year the Event Horizon Telescope consortium released the image of a black hole over 50 million light years away. Also the LIGO and Virgo gravitational wave observatories detected two neutron stars colliding which set off a frenzy of activity by astronomers who viewed the aftermath from gamma rays to microwaves.

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

Addendum

Kepler Spacecraft. Credit NASA.

Kepler Spacecraft studied a single patch of sky for several years and has discovered the bulk of the exoplanets. Credit NASA.

Pluto

Enhanced color portrait of Pluto by the New Horizons spacecraft. Credit: NASA/JHUAPL/SwRI

First closeup of Ultima Thule

486958 Arrokoth original dubbed Ultima Thule by the New Horizons team on approach combining low resolution image with the high resolution monochromatic image shows the body in almost true color. Credit NASA/JHAPL/SWRi

Black hole in M87

The first image of the black hole in M87. Credit Event Horizon Telescope.

Neutron Star Collision GW 170817 timeline

Neutron Star Collision GW 170817 timeline. Horizontal axis in seconds (exponential). Click on chart to enlarge. From the High Energy Stereoscopic System website.

07/22/2019 – Ephemeris – Apollo 11 heads home

July 22, 2019 Comments off

Ephemeris for Monday, July 22nd. Today the Sun will be up for 15 hours and 1 minute, setting at 9:19, and it will rise tomorrow at 6:19. The Moon, 2 days before last quarter, will rise at 12:27 tomorrow morning.

50 years ago after a bit more than 2 hours working on the surface of the Moon, Neil Armstrong and Buzz Aldrin climbed back into the Lunar Module to stow the 48 pounds of samples they had taken and to rest up for the return trip to the Command Module and Mike Collins circling above them. After docking, they transferred the samples to the command module and jettisoned the LM. Then they fired the Service Module engine for 2 and a half minutes to send them back to Earth, and landing them in the Pacific Ocean on July 24th. Not knowing if they were contaminated by lunar pathogens, the crew was quarantined for 21 days. The crew was released from Quarantine on August 10th.

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

Addendum

Lunar lander’s ascent module approaching the command module with Earth in the distance. Credit NASA.

The crew in a like raft in bio contamination suits after splashdown.. Credit NASA.

Left to right Neil Armstrong, Michael Collins, Buzz Aldrin accept greeting form President Nixon on the USS Hornet. Credit NASA.

07/19/2019 – Ephemeris – 50 years ago tomorrow humankind set foot on the Moon

July 19, 2019 Comments off

Ephemeris for Friday, July 19th. Today the Sun will be up for 15 hours and 7 minutes, setting at 9:22, and it will rise tomorrow at 6:16. The Moon, 3 days past full, will rise at 11:14 this evening.

On this day, 50 years ago the combined Apollo 11 spacecraft Command and Service module with attached Lunar Module dropped into orbit of the Moon. The crew spotted a glow coming from the Aristarchus region, still on the night side of the Moon. Armstrong and Aldrin entered the LM to power it up and to get it ready for landing. The next day they undocked from the Command Module and began their 2 hour 33 minute descent to the Moon’s surface. As they neared the surface The astronauts found out they were going to miss the planned landing area and would land in a more boulder strewn area. Armstrong took control and guided the LM to a safe landing with less than 30 seconds of fuel remaining. The Eagle had landed.

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

Addendum

Crew of Apollo 11

Left to right Neil Armstrong, Mission Commander; Michael Collins, Command Module Pilot; and Buzz Aldrin, Lunar Module Pilot. Credit: NASA.

Apollo 11 launch

The Saturn V for the Apollo 11 mission lifts of from Pad 39A. Credit: NASA.

Aldrin with the PSEP instrument looking back at the LM. Credit NASA/Neil Armstrong.

Lunar Reconnaissance Orbiter image of the Apollo 11 landing area. Compare the location od the objects in the picture above with this image.  The flag was blown down by the lift off of the Ascent module when the Astronauts left the Moon. Credit NASA/LRO.

07/16/2019 – Ephemeris – 50 years ago today the Apollo mission left for the Moon

July 16, 2019 Comments off

Ephemeris for Tuesday, July 16th. Today the Sun will be up for 15 hours and 12 minutes, setting at 9:25, and it will rise tomorrow at 6:13. The Moon, at full today, will rise at 9:30 this evening.

50 years ago today at 11:32 a.m. Eastern Daylight Time the most powerful rocket ever built roared into life. The Saturn V, a three stage rocket, 363 feet tall, which in turn launched two spacecraft, the Command and Service modules, and the Lunar Module, and three astronauts on their journey to destiny, Neil Armstrong, Edwin (Buzz) Aldrin, and Michael Collins. It was the start of the Apollo 11 mission. It happens that tonight the namesake of the rocket, the planet Saturn is to the right of the Moon. At launch the Moon was two days old, a thin crescent in the west that evening. Four days later they would be orbiting the Moon, and Armstrong and Aldrin would be descending to the Moon’s surface.

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

Addenda

Apollo 11

Crew of Apollo 11

Left to right Neil Armstrong, Mission Commander; Michael Collins, Command Module Pilot; and Buzz Aldrin, Lunar Module Pilot. Credit: NASA.

Apollo 11 launch

The Saturn V for the Apollo 11 mission lifts of from Pad 39A. Credit: NASA.

The Moon and Saturn tonight

The Moon and Saturn tonight, 11 p.m. July 16, 2019. In reality the Moon will be so bright that Saturn will be almost overwhelmed. Created using Stellarium.

Here’s an excellent podcast series from the BBC:  13 Minutes to the Moon.

Partial Lunar Eclipse

The partial lunar eclipse today is not mentioned in the program because it is not visible locally.

Partial Lunar Eclipse of July 16, 2019. Click on image to enlarge. Credit NASA/GSFC/F. Espenak.

07/15/2019 – Ephemeris – The Apollo 1 tragedy

July 15, 2019 Comments off

Ephemeris for Monday, July 15th. Today the Sun will be up for 15 hours and 14 minutes, setting at 9:25, and it will rise tomorrow at 6:12. The Moon, 1 day before full, will set at 5:48 tomorrow morning.

On January 27th, 1967 the crew of Apollo 1 were running a dress rehearsal of their upcoming launch. On board were Gus Grissom, veteran of the Mercury and Gemini programs, Ed White the first American to walk in space on Gemini 4, and rookie astronaut Roger Chaffee from my home town of Grand Rapids, Michigan. Five and a half hours after the test started one of the crew called out “Fire in the cockpit”. In a very few minutes the astronauts were dead. They were running in a pure oxygen atmosphere at a bit above atmospheric pressure and a spark may have ignited the flammable materials in the spacecraft. The accident delayed the program nearly 2 years as the capsule was redesigned.

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

Addendum

Apollo 1 crew

Left to right: Virgil I. (Gus) Grissom, veteran of the second Mercury flight and Gemini 3, the first manned Gemini flight; Edward H. White first American space walker on Gemini 4, and rookie Roger B. Chaffee. Credit: NASA.

Apollo 1 spacecraft after the fire

The outside of the Apollo 1 capsule after thr fire that took the three astronaut’s lives. Credit: NASA.

06/11/2019 – Ephemeris – The crater Copernicus on the Moon

June 11, 2019 Comments off

Ephemeris for Tuesday, June 11th. Today the Sun will be up for 15 hours and 31 minutes, setting at 9:28, and it will rise tomorrow at 5:56. The Moon, 1 day past first quarter, will set at 3:26 tomorrow morning.

Tonight, visible on the waxing gibbous Moon in binoculars or a small telescope the terminator, the sunrise line crosses the prominent crater Copernicus. This crater is nearly half way from the top to the bottom of the Moon. It is 56 miles (93 km) in diameter and 2 miles (3.5 k m) deep. The low Sun angle accentuates the depth of the crater. As large craters goes, Copernicus is rather new, being somewhat younger than 1.1 billion years old, a quarter of the Moon’s age. A dramatic image taken by the Lunar Orbiter spacecraft in 1966, in preparation for the Apollo lunar landings of an oblique view of the crater peeking over a crater wall was, at that time, dubbed the Picture of the Century”.

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

Addendum

Binocular Moon

The Moon tonight, June 11, 2019 showing the crater Copernicus. Created using Virtual Moon Atlas.

Closeup of Copernicus

Closeup of Copernicus with the small double crater Fauth south of it. Created using Virtual Moon Atlas.

Picture of the Century

Picture of the Century taken by the lunar Orbiter 2. Copernicus in an oblique photo from the south. Not the double crater Fauth at the bottom of the Image. Credit: NASA/Lunar Orbiter Image Recovery Project (LOIRP).