11/20/2020 – Ephemeris – Martian Trojan asteroid may have come from our Moon

This is Ephemeris for Friday, November 20th. Today the Sun will be up for 9 hours and 22 minutes, setting at 5:09, and it will rise tomorrow at 7:48. The Moon, 1 day before first quarter, will set at 10:39 this evening.

The way gravity works there are several gravitational sweet spots called Lagrangian points between orbital bodies. Two of those points, 60 degrees ahead of and behind a planet in its orbit, are called L4 and L5. Bodies at these points are called Trojan asteroids. Because the first ones found in Jupiter’s orbit were named after warriors of the Trojan War. What was discovered recently was that one of the planet Mars’ L5 Trojans is not like the others. It has a different composition as analyzed by a spectrograph. It reflects light like the Earth’s Moon, while the others appear to have come from Mars itself. Perhaps an ejected piece of the Moon made it out to Mars orbit. We know small meteoroids can make it planet to planet, maybe huge chunks can make it too.

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

Addendum

Mars and its Trojan asteroids including 101429 the asteroid that is spectroscopicly like the Moon. The other Trojans appear to have come from Mars itself. I tend to be a stickler for image accuracy: The Mars image is upside down and reversed, while the rest of the diagram is essentially correct other than being way out of scale. Credit Armagh Observatory and Planetarium (AOP) in Northern Ireland.

10/06/2020 – Ephemeris – Mars is closest today, also the Draconid meteors are at peak

This is Ephemeris for Tuesday, October 6th. Today the Sun will be up for 11 hours and 25 minutes, setting at 7:13, and it will rise tomorrow at 7:48. The Moon, 3 days before last quarter, will rise at 9:46 this evening.

Today Mars is at its closest to the Earth of this close approach, what astronomers call an apparition. The last close approach was at the end of July two years ago. It is still pretty small in telescopes. However being this close, 38.6 million miles (62.1 million kilometers) away, it is actually slightly brighter than Jupiter. Check them out. Mars is the bright orange tinged star in the east while Jupiter is in the south-southwest at 9 pm tonight. It’s still a week before Mars lines up with the Earth and Sun in opposition. Mars is closer now because it is moving away from the Sun in its orbit. We are at the peak of a weak meteor shower most years. It’s the Draconids, which appear to come from the head of Draco the dragon near the bright star Vega, nearly overhead in the evening.

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

Addenda

Mars

Inner solar system on October 6, 2020 showing Mars at it’s closest to the Earth. Note the motion of the planets and space probes are counterclockwise. Mars is moving away from its closest point to the Sun at about the 2 o’clock point in its orbit. Note that at this time Mars, the Earth and Sun are not yet in line, so Mars isn’t directly opposite the Sun from the Earth, called opposition. That will occur on the 13th. The Mars 2020 Rover “Percy” has a bit more than 4 months to go to reach Mars. Credit: NASA Eyes App https://eyes.nasa.gov/

Draconid Meteor Shower

The Draconid radiant in the head of Draco. Looking high in the northwest at 9 pm October 6th. The source of the Draconids is the Comet 21P/Giacobini-Zinner. The stars of the Summer Triangle are named.

Comet Giacobini-Zinner was the third comet I had ever seen. It was through my newly completed 8″ reflector in 1959, when the comet was quite close to the Earth. The comet just skims the Earth’s orbit at its perihelion, so the Earth passes through its trail of debris each year at this time. The meteor shower is very weak, 5-10 meteors an hour, unless the comet is near to the Earth at the time, as it was in 2018. The comet has an orbital period of about 6.6 years, so this year’s peak isn’t supposed to be the best. However this year me might have two mini peaks tonight in the 9 to 10 pm hour as the Earth is expected to pass through two old meteoroid trails. according to the International Meteor Organization’s 2020 Meteor Shower Calendar we are expected to pass through the 1704 trail at 9:25 pm, EDT and the 1711 trail at 9:57 pm EDT. This is October 7th at 1:25 UT and 1:57 UT. The normal projected peak is October 8 at 12:30 UT, that’s Thursday at 8:30 am, after sunrise.

08/03/2020 – Ephemeris – What is the Perseverance Rover going to do on Mars?

This is Ephemeris for Monday, August 3rd. Today the Sun will be up for 14 hours and 33 minutes, setting at 9:05, and it will rise tomorrow at 6:33. The Moon, at full today, will rise at 9:35 this evening.

The Mars Perseverance Rover looks a lot like the Curiosity Rover that landed on Mars in Gale Crater almost exactly 8 years ago (Earth years that is). It has more and better cameras, some different tools on its arm. It will have a laser like Curiosity. It can take core samples and store them in sealed tubes for later return to the Earth. It has an experimental helicopter drone named Ingenuity that must, like the rover be autonomous since it cannot be controlled in real-time from the Earth. The main mission this time is to look for signs of life in a spot we know water had flowed in the ancient past. The surface water and the life is long gone, but there might be signs that it might have been present in the distant past before Mars lost most of its atmosphere and water.

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

Addendum

Artist rendition of the Mars 2020 “Endurance” Rover. Credit NASA.

Artist’s concept of the Mars Helicopter “Ingenuity”. Credit: NASA/JPL-Caltech.

07/30/2020 – Ephemeris – This morning is the first opportunity to launch the Perseverance Rover to Mars

This is Ephemeris for Thursday, July 30th. Today the Sun will be up for 14 hours and 42 minutes, setting at 9:10, and it will rise tomorrow at 6:28. The Moon, 3 days past first quarter, will set at 3:11 tomorrow morning.

This morning is the scheduled launch of the Mars 2020 Rover named Perseverance. The launch will have or had launched at 7:50 am. Or the whole thing was scrubbed for today. I can’t tell, I recorded this last Sunday night. To hit a spot on Mars less than six miles in diameter after a six and a half month coasting flight is quite a fete. Mars is not only moving in orbit of the Sun, but also rotating. The aeroshell the rover is packed in must hit the Mars atmosphere in the right place, and the right time despite the light time from Mars of 11 minutes, 22 seconds. It will take 6 minutes, 50 seconds for the rover to land after it hits the top of Mars’ atmosphere. So it will have landed one way or another before we get the signal that it hit the atmosphere.

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

Addendum

Atlas V with Mars 2020 Rover aboard on launch pad. Click on the image to enlarge. Credit: United Launch Alliance (ULA).

07/28/2020 – Ephemeris – The Mars Endurance Rover may launch to Mars on Thursday

This is Ephemeris for Tuesday, July 28th. Today the Sun will be up for 14 hours and 47 minutes, setting at 9:12, and it will rise tomorrow at 6:26. The Moon, 1 day past first quarter, will set at 1:49 tomorrow morning.

This Thursday at 7:50 am is the first opportunity to launch the Mars 2020 or Perseverance Rover to Mars to arrive on February 18th 2021. The rover will be launched on a United Launch Alliance Atlas 5/Centaur rocket with 4 solid boosters. To send a payload to Mars one must launch within a specific window of time called a launch period. This was originally from July17 to August 11th. Some issues with testing caused a delay to July 30th. The launch period was extended to August 15th. Miss that and it’s a wait of 26 months until Earth and Mars are in the same relative position to try again. The landing area or ellipse is less than 6 miles long on the long axis and partially overlaps an ancient dried river delta that flowed into Jezero crater.

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

Addendum

An artist’s concept of the Mars 2020 Rover launch. The rocket is an Atlas V with 4 solid boosters and a Centaur upper stage. Credit NASA.

 

05/08/2020 – Ephemeris – A look at Mars 2020 Endurance Rover’s target crater: Jezero

This is Ephemeris for Friday, May 8th. Today the Sun will be up for 14 hours and 34 minutes, setting at 8:56, and it will rise tomorrow at 6:21. The Moon, 1 day past full, will rise at 10:43 this evening.

The Mars 2020 Rover will be launched on July 17th or thereabouts to land at the crater Jezero* on the Red Planet. What’s the big deal about Jezero? In very early Martian history the crater was filled with water with a river flowing into it. What’s left is a dry river delta. The landing ellipse target for the rover will land it near the leading edge of that delta. Spectral analysis from the Mars Reconnaissance Orbiter has detected clays that can contain, on Earth, fossils of single celled organisms. The rover is not equipped with a powerful enough microscope to detect them so they will be cached to be returned to the Earth sometime in the future as one of its objectives. Scientists believe that Mars was friendly for life for only a billion years or so.

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

Addendum

Jezero is pronounced like the biblical character Jezebel.

Jezero Crater on a map by the Mars Orbiter Laser Altimeter (MOLA) instrument on the Mars Global Surveyor spacecraft (1996-2006). Colors code by altitude (blue-low to red-high). Click on the image to enlarge. Credit NASA/JPL.

The Jezero crater from the European Space Agency’s Mars Express Orbiter. Jezero is 30.4 miles (49.0 km) in diameter. Note the river delta on the left (west) forming a lake with an outlet on the right. Click on the image to enlarge. Credit: NASA/JPL/MSSS/ESA.

Mars Endurance Rover’s planned landing ellipse partially overlapping the dried up river delta. Click on the image to enlarge. Credit: NASA/JPL.

Delta of ancient river that flowed into a lake in the Jezero crater. Color coded based on minerals present. Click on the image to enlarge. Credit NASA.

02/17/2020 – Ephemeris Extra – The Moon will cover the planet Mars in morning twilight tomorrow, Tuesday the 18th.

Sorry, I missed this until now. Tomorrow morning the 18th Mars will be occulted by the Moon. For Northern Lower Michigan Mars will disappear shortly after 7:10 a.m. The exact time depends on your location, so I can’t be more specific.  At that time the Moon and Mars will be in the southeastern sky. Mars is now first magnitude, but will fare poorly in the morning twilight, so I’d suggest finding the Moon and Mars at least 15 minutes earlier with binoculars or telescope. Mars will reappear at the Moon’s unlit side around 8:37 a.m. This is after sunrise, so a telescope will be required to spot it.  Hoping for clear skies, though the weather forecast isn’t promising.

A map of where the occultation of Mars will be visible. Created using Occult4.

Where Mars will disappear at the Moon’s sunlit edge. Created using Stellarium.

Mars will reappear at the Moon’s unlit edge around 8:36 a.m. give or take. Created using Stellarium.

06-18-2019 – Ephemeris – Mercury and Mars will be seen together tonight

Ephemeris for Tuesday, June 18th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31, and it will rise tomorrow at 5:56. The Moon, 1 day past full, will rise at 10:49 this evening.

This evening the Planets Mercury and Mars will appear less than a moon-width apart in the evening twilight. Mercury, the brighter of the two, by a factor of 4 times, will be visible first, at about 10:15 p.m. very low in the west-northwest. Mars will be immediately below it by less than the width of the Moon. At that time they will be a bit less than the width of your fist held at arm’s length above the horizon. Binoculars are the best way to spot them. Mercury will continue to move eastward in the sky away from Mars. Until after it reaches its greatest separation from the Sun on the 23rd. It will then head back and pass at a much greater distance below Mars on July 5th. This is the best chance to spot Mercury in the evening sky this year.

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

Addendum

Mercury and Mars this evening at 10:30 p.m., June 18, 2019. Created using Stellarium.

11/26/2018 – Ephemeris – NASA’s InSight spacecraft lands on Mars this afternoon

Ephemeris for Monday, November 26th. The Sun will rise at 7:54. It’ll be up for 9 hours and 11 minutes, setting at 5:05. The Moon, half way from full to last quarter, will rise at 8:43 this evening.

This afternoon NASA’s InSight spacecraft will land on Mars. It will drill into the martial soil to place a temperature probe to measure Mars’ heat flow to determine the interior temperature of Mars. It will also deploy a seismometer to detect marsquakes and seismic waves generated by meteorite impacts to ascertain the interior structure of the planet. The entry, decent and landing or EDL as it’s called begins at 2:47 p.m. Eastern Standard Time, with landing 6 minutes, 45 seconds later. The Jet Propulsion Laboratory calls it Seven Minutes of Terror. The spacecraft is on its own so everything has to go right. Mars is 8 light minutes away. The spacecraft will be on the ground one way or the other for over a minute by the time we get word that the spacecraft has entered the atmosphere of Mars.  NASA-TV, available on the Internet, starts its coverage at 2 p.m. Eastern Standard Time.

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

Addendum

InSight landing infographic. Credit Emily Lakdawalla for the Planetary Society. Here’s her caption: Advance predictions for the details of InSight’s landing made several weeks beforehand. Adjustments to the trajectories of InSight or Mars Reconnaissance Orbiter may change these times by up to several seconds, as could weather on landing day. All times include 8.1 minutes of one-way light time delay (accounting for the time it takes signals to travel from Mars to Earth). Abbreviations used in the labels: EDL = entry, descent, and landing; E = entry; T = touchdown; h m s = hours, minutes, and seconds; UT = Universal Time (subtract 8 hours for Pacific, 5 for Eastern, add 1 for European time, add 8 for Japan).  Click on image to enlarge. 

To see Emily’s post with a lot more information, click on this URL:  http://www.planetary.org/blogs/emily-lakdawalla/2018/mars-insight-landing-preview.html.  The post has a link to NASA’s 68 page pdf Mars InSight Landing Press Kit, which covers all aspects of entry, descent and landing, the Mars Insight components, and science instruments, and what they expect to learn about Mars’ interior.

Components of the Mars InSight Lander. Credit: NASA/JPL-Caltech – Adrian Mann/Tobias Roetsch/Future Plc. Hat Tip to Space.com

08/02/2018 – Ephemeris – Has liquid water been found on Mars?

Ephemeris for Thursday, August 2nd. The Sun rises at 6:30. It’ll be up for 14 hours and 37 minutes, setting at 9:07. The Moon, 2 days before last quarter, will rise at 12:09 tomorrow morning.

The European Space Agency has announced the possible discovery of liquid water beneath Mars’ southern polar cap. Perhaps it’s like the lakes found under Earth’s Antarctic ice sheet. The discovery was made by the Mars Express orbiter’s ground penetrating radar. Mars south polar cap is primarily made of water ice up to 3.7 kilometers thick, covered in winter by a meter, give or take, thickness of carbon dioxide ice, what we call dry ice. Mars elliptical orbit happens to make southern hemisphere summers short and hot, and winters long and especially cold. Liquid water could exist several kilometers below the martian surface. Mars’ internal heat flow is what NASA’s InSight lander, now en route to Mars is going to tell us.

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

Addendum

Mars Express detects water buried under the south pole of Mars. Click on the image to enlarge. Credit: European Space Agency (ESA)