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

February 17, 2020 Comments off

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.

Occultation map

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

Mars Occultation Start

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

Mars Occultation End

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

June 18, 2019 Comments off

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-Mars Conjunction

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

November 26, 2018 Comments off

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

Categories: Ephemeris Program, Mars, NASA

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

August 2, 2018 Comments off

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

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

07/30/2018 – Ephemeris – Early tomorrow morning Mars will be the closest to is in 15 years

July 30, 2018 Comments off

Ephemeris for Monday, July 30th. The Sun rises at 6:26. It’ll be up for 14 hours and 44 minutes, setting at 9:10. The Moon, 3 days past full, will rise at 10:51 this evening.

Mars’ closest approach to the Earth since August 27, 2003 is tomorrow at about 3:51 a.m. at a distance of 35.8 million miles (57.6 million km). The last really close approach of Mars was on August 27, 2003 when it was about 600 thousand miles (a million km) closer. That close approach was probably the closest in 50 thousand years. Mars and the Earth get close in their orbits about every 26 months. But because Mars has a much more elliptical orbit than the Earth, the very best close encounters occur every 15 or 17 years. Despite the fact that we have satellites that orbit Mars and two rovers operating on its surface, amateur astronomers still challenge themselves to observe and photograph Mars at its very closest.

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

Addendum

Mars closest approaches 2003-2018

Mars’ closest approaches to the Earth in the period 2003 to 2018 also showing the apparent sizes of the planet at each approach. Click on image to enlarge. Created using my LookingUp program and Cartes du Ciel (Sky Charts).

 

07/27/2018 – Ephemeris – Mars is at opposition from the Sun today

July 27, 2018 Comments off

Ephemeris for Friday, July 27th. The Sun rises at 6:23. It’ll be up for 14 hours and 50 minutes, setting at 9:14. The Moon, at full today, will rise at 9:16 this evening.

The planet Mars was at opposition with the Sun early this morning, that is opposite the Sun in the sky. It is a time when a planet rises at sunset and sets at sunrise. For us it will rise tonight at 9:40 p.m. 26 minutes after sunset and will set tomorrow at 6 a.m., 24 minutes before sunrise. This odd behavior is due to the fact that Mars is actually south of a lime from the Sun through the Earth. Mars’ orbit is tilted to the Earths’ so it will appear lower in the sky as one would expect for a planet in its position. Today Mars is 35.9 million miles (57.7 million km) away. In four days it will be a bit closer to us due to its elliptical orbit taking it a bit closer to the Sun. How much closer? About 93,000 miles (150,000 km) to us.

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

Addendum

Retrograde Mars Path 2018

This chart is shown with the horizontal being parallel to the ecliptic, which is the horizontal line near the top of the image.  Created using Cartes du Ciel (Sky Charts).

Retrograde motion explained

Created using Cartes du Ciel (Sky Charts).

Mars at the meridian at opposition

Mars on opposition day, July 27, 2018 at 1:55 a.m. as it crossed the meridian due south. In the Interlochen/Traverse City area a bit south of 45 degrees north latitude. Mars appears a an altitude of slightly less than 20 degrees altitude. Created using Stellarium.

Update

Mars at opposition and the full Moon

Mars at opposition and the full Moon at 2:01 a.m. July 27, 2018. I thought I’d go out near the Mars transit time this morning and photograph the Moon and Mars. Earlier we had a pop-up rain shower, and the clouds were clearing out. Got a lucky shot.

07/26/2018 – Ephemeris – How can you get to Mars – the Hohmann transfer orbit

July 26, 2018 Comments off

Ephemeris for Thursday, July 26th. The Sun rises at 6:22. It’ll be up for 14 hours and 53 minutes, setting at 9:15. The Moon, 1 day before full, will set at 6:06 tomorrow morning.

How does one get a spacecraft to another planet, like Mars? One might think to wait until the two planets are closest and zip across. That would take more energy than we are capable of. We cab barely escape the Earth and get a spacecraft into solar orbit. Also one needs energy to slow down to be captured by the planet if one wants to orbit it. The most economical way was devised way before the space age by Walter Hohmann, a German scientist in 1925. The idea is to launch a spacecraft with enough velocity to reach the other planet half way around the Sun, so the transfer orbit is tangent to both the Earth’s and the planet’s orbit. Transit times to Mars would be in the range of 7 months. The InSight lander is currently on such a trajectory.

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

Addendum

Hohmann transfer orbit

Hohmann transfer orbit. Credit Planetary Society-Myron Kayton

Hohmann orbit to Mars

A Hohmann lowest energy transfer orbit to Mars. This diagram is for the Mars Exploration Rovers Spirit and Opportunity orbits, launched in 2003, arrived in 2004. Solid planets, Spirit launch and arrival. Ghost planets, Opportunity launch and arrival. Credit NASA/JPL.