Archive

Archive for March, 2021

03/31/2021 – Ephemeris – Let’s search for the naked-eye planets for this week

March 31, 2021 Comments off

This is Bob Moler with Ephemeris for Wednesday, March 31st. Today the Sun will be up for 12 hours and 44 minutes, setting at 8:09, and it will rise tomorrow at 7:23. The Moon, 3 days past full, will rise at 12:11 tomorrow morning.

Let’s search for the naked-eye planets for this week. Unfortunately the only one you’ll find in the evening is Mars. It can be found in the west-southwest at 9 pm tonight, above the orange star Aldebaran in the face of Taurus the bull. Mars will set at 1:54 am. Right now three of the other four naked eye planets are just west of the Sun in the Morning sky. Venus is now below and just a bit east of the Sun, setting four minutes after sunset. Only Saturn and Jupiter are at a far enough angle from the Sun to be just spotted in the morning twilight. Saturn will rise at 5:10 am, with Jupiter rising 31 minutes later. By 6:30 am they will be low in the southeast. The Sun is rising earlier by 2 minutes a day now, while sunset is nearly matching that pace in the opposite direction.

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

Addendum

Mars in the evening
Mars with nearby stars n the fading twilight of 9 pm, about 50 minutes after sunset, tonight March 31, 2021. Created using Stellarium.
Saturn and Jupiter low in the sky at 6 am tomorrow, April 1, 2021, about an hour and a half before sunrise. Created using Stellarium.
The waning gibbous Moon as it might appear in a small telescope or binoculars
The waning gibbous Moon as it might appear in a small telescope or binoculars at 6 am tomorrow, April 1, 2021. Created using Stellarium.

The new version of Stellarium I’m using, 0.21.0, has new textures for the Moon that are more realistic and show finer detail than earlier versions. If the Moon is enlarged to fill the window, clicking on a feature will reveal its name.

Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on March 31, 2021. The night ends on the left with sunrise on April 1st. Click on the image to enlarge. Created using my LookingUp program.

03/30/2021 – Ephemeris – Apophis asteroid will not hit the Earth in the next 100 years, if ever

March 30, 2021 Comments off

This is Bob Moler with Ephemeris for Tuesday, March 30th. Today the Sun will be up for 12 hours and 41 minutes, setting at 8:08, and it will rise tomorrow at 7:24. The Moon, 2 days past full, will rise at 10:50 this evening.

When the asteroid Apophis was discovered in 2004, it was calculated to have a 2.7% chance of hitting the Earth on Friday the 13th, no less, in April 2029. That’s 8 years from now. Except it won’t. We knew that early on. The next possible collision date would be on April 13, 2036 if Apophis passes through a hypothetical “keyhole” in time and space on its 2029 pass setting up a trajectory that would intercept the Earth on that date. Recent radar studies using pulses sent from Goldstone in California, off the asteroid, and received by the Green Bank Radio Telescope in West Virginia have refined the orbit to as to preclude any collision of Apophis with the Earth for at least the next 100 years. So Apophis was removed from the Jet Propulsion Laboratory’s asteroid risk list last Thursday.

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

Addendum

The orbits of Apophis and Earth and their locations on April 24, 2021. The proximity of Apophis to the Earth in March allowed radar observations that ruled out a collision with the Earth for at least the next 100 years. Image credit: JPL Small-Body Database Browser.

03/29/2021 – Ephemeris – NASA will fly spacecraft Psyche to asteroid 16 Psyche

March 29, 2021 1 comment

This is Ephemeris for Monday, March 29th. Today the Sun will be up for 12 hours and 38 minutes, setting at 8:07, and it will rise tomorrow at 7:26. The Moon, 1 day past full, will rise at 9:28 this evening.

In the summer of 2022, about 15 months from now, NASA will launch a spacecraft called Psyche on a SpaceX Falcon Heavy rocket to 16 Psyche, an asteroid. 16 Psyche is a very special asteroid. It is mostly made of iron and nickel like iron meteorites and the cores of planets like the Earth. The spacecraft will be launched to get a gravity assist from Mars and will be using an ion engine to make its way to 16 Psyche and orbit it at various altitudes to see if it really is the remnant core of a protoplanet that was destroyed by collisions with other large asteroids. It would be of great interest for the future of asteroid mining companies for the precious metals it might contain. It’s big and has an average diameter of 140 miles (225 kilometers).

<p value="<amp-fit-text layout="fixed-height" min-font-size="6" max-font-size="72" height="80">The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.The astronomical 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 Psyche spacecraft orbiting the asteroid 16 Psyche
An artist’s concept of the Psyche spacecraft orbiting the asteroid 16 Psyche. The spacecraft will be sent past Mars for a gravity assist, and also use ion thrusters to speed it on its three and a half journey to the asteroid. Credit: NASA/JPL-Caltech/Arizona State Univ./Space Systems Loral/Peter Rubin

03/26/2021 – Ephemeris – Venus passes beyond the Sun this morning

March 26, 2021 Comments off

This is Ephemeris for Friday, March 26th. Today the Sun will be up for 12 hours and 29 minutes, setting at 8:03, and it will rise tomorrow at 7:32. The Moon, 2 days before full, will set at 7:24 tomorrow morning.

Early this morning the planet Venus was in conjunction with the Sun. It was a superior conjunction, meaning it was out beyond the Sun. When Venus ducks between the Earth and the Sun it’s called an inferior conjunction. Here the words superior and inferior do not have their normal meanings. Inferior means inside and superior means outside. Indeed, I find inferior conjunctions far superior to superior conjunctions. For the inferior conjunction, Venus is close to us, so it appears big, bigger than Jupiter in telescopes. It only disappears in the glare of the Sun for 8 days or so. Around superior conjunctions Venus is tiny, and it disappears in the glare of the Sun for 50 or more days. Rare inferior conjunctions will see Venus cross or transit the face of the Sun.

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

Addendum

SOHO image of the Sun with Venus below

Solar and Heliospheric Observatory (SOHO) LASCO C2 coronagraph image of the Sun and Venus below and beyond the Sun. The white circle shows the size of the photosphere of the Sun.

03/25/2021 – Ephemeris – NASA successfully tests the core stage of the Artemis Moon Rocket

March 25, 2021 Comments off

This is Ephemeris for Thursday, March 25th. Today the Sun will be up for 12 hours and 25 minutes, setting at 8:02, and it will rise tomorrow at 7:34. The Moon, 3 days before full, will set at 6:57 tomorrow morning.

Last week’s 8-minute static fire test of the four Shuttle main engines of the core stage of the NASA’s Space Launch System or SLS rocket was an apparent success at the Stennis Space Center in southern Mississippi. This came after a failed test two months ago. The core stage will be refurbished and floated through the Gulf, around the tip of Florida to Cape Canaveral where the solid boosters are waiting to be mated to it in the Vertical Assembly Building. It will be used for the Artemis 1 mission to be launched late this year. That mission will take an uncrewed  Orion Crew Capsule and European Service Module to the Moon for several orbits close and more distant from it before returning to the Earth. The entire mission could take nearly a month.

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

Addendum

Views of the SLS Core Stage green run test

Views of the SLS Core Stage green run test. Credit NASA via scitechdaily.com.

03/24/2021 – Ephemeris – Let’s search for the naked-eye planets for this week

March 24, 2021 Comments off

This is Ephemeris for Wednesday, March 24th. Today the Sun will be up for 12 hours and 22 minutes, setting at 8:00, and it will rise tomorrow at 7:36. The Moon, 3 days past first quarter, will set at 6:26 tomorrow morning.

Let’s search for the naked-eye planets for this week. Unfortunately the only one you’ll find in the evening is Mars. It can be found high in the west-southwest at 9 pm tonight, above the orange star Aldebaran in the face of Taurus the bull, between it and the much higher star Capella in the west northwest. Mars will set at 2:01 am. Right now three of the other four naked eye planets are just west of the Sun in the Morning sky. Venus is now below and just a bit west of the Sun. Only Saturn and Jupiter are at a far enough angle from the Sun to be just spotted in the morning twilight. Saturn will rise at 5:35 am, with Jupiter rising a half hour later. By 7 am they will be low in the southeast.

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

Addendum

Mars in the evening

Mars appears above Aldebaran and the letter V of stars of the Hyades which is the face of Taurus the bull tonight March 24, 2021. This image is for 9 pm. or about an hour after sunset. Created using Stellarium.

Binocular Moon

The waxing gibbous Moon as it might be seen in binoculars tonight at 9 pm, March 24, 2021. Created using Stellarium.

Morning planets

Jupiter and Saturn low in the southeast at 7 am tomorrow morning, March 25, 2021. Note that they will probably appear dimmer than shown. Created using Stellarium.

Planets and the Moon on a single night

Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on March 24, 2021. The night ends on the left with sunrise on the 25th. Venus is too close and south of the Sun to be plotted. Click on the image to enlarge. Created using my LookingUp program.

03/23/2021 – Ephemeris – The Moon tonight: Bay of Rainbows

March 23, 2021 Comments off

This is Bob Moler with Ephemeris for Tuesday, March 23rd. Today the Sun will be up for 12 hours and 19 minutes, setting at 7:59, and it will rise tomorrow at 7:37. The Moon, 2 days past first quarter, will set at 5:50 tomorrow morning.

A look at the Moon tonight will reveal that the sunrise line, or terminator has almost completely revealed the large Sea of Showers or Mare Imbrium to the upper left of the center of the gibbous disk. At the extreme upper left nearly completely in sunlight a very popular feature, the Bay of Rainbows or Sinus Iridium. It’s a colorful name for something that’s as gray as the rest of the Moon. It looks like a bay off of Imbrium, and has an arch like a rainbow. Its arch is the Jura Mountains, which jut into Mare Imbrium at Cape Heraclide, just catching sunlight, and Cape Laplace farther into morning. What’s cool is catching it as the sunlight is hitting the mountains while the convex floor, following the Moon’s curvature is only partially illuminated.

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

Addendum

The Moon with Sinus Iridium

The Moon a little before how it will appear tonight highlighting Sinus Iridium. By tonight the floor of Sinus Iridium should be pretty much sunlit, and the Jura mountains completely lit. Created using Virtual Moon Atlas.

 

03/22/2021 – Ephemeris – The Moon and the week

March 22, 2021 Comments off

This is Bob Moler with Ephemeris for Monday, March 22nd. Today the Sun will be up for 12 hours and 16 minutes, setting at 7:58, and it will rise tomorrow at 7:39. The Moon, 1 day past first quarter, will set at 5:08 tomorrow morning.

The Moon tonight is about as far north in the sky as it gets this month, and being six days before full, and this full Moon is the first full moon of spring, that means Easter is less than two weeks away. Did you notice that a week is nearly equal to a quarter of the Moon’s orbit of the Earth? If you look at a calendar that has the Moon’s phases on it the phases are 7 or 8 days apart. It’s a good thing that no one decided to adjust the length of the week to accommodate the Moon’s phases. It’d be hard to plan your weekend. Our calendar is pretty screwed up as it is with months of 28, 29, 30 and 31 days all set by politicians… Roman politicians at that. I haven’t heard much about calendar reform lately, so I guess we’re stuck with it.

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

Addendum

I wrote the above before actually checking out the historical origin of the time period we call a week. It turns out that the week is really related to a quarter of a lunation or lunar month. The Babylonians fixed the fact that seven days is a bit less than a quarter of a lunation by adding a day or two to the last week of the month, so the next month’s new moon started on the same day of the week.

Here the new moon is defined as the first appearance of the Moon in the evening sky after disappearing from the morning sky. We currently define the new moon as the Moon’s solar conjunction. Its first appearance in the evening sky would generally be the next day, or rather evening. The numbering still works out. Our new moon is day zero of the lunar month.

03/19/2021 – Ephemeris – Enjoy this last full day of winter!

March 19, 2021 Comments off

This is Ephemeris for Friday, March 19th. Today the Sun will be up for 12 hours and 7 minutes, setting at 7:54, and it will rise tomorrow at 7:45. The Moon, 2 days before first quarter, will set at 2:23 tomorrow morning.

Spring is almost here. It will arrive at 5:37 tomorrow morning, so this is the last full day of winter, such as it was. That point in time and the point in the sky where the Sun crosses the celestial equator, the imaginary line in the sky above the Earth’s equator, heading northward is called the vernal equinox. Vernal means spring and equinox means equal night, meaning that day and night are equal, which they actually were last Tuesday. Since western civilization has spread south of the equator where the seasons are reversed, our Northern Hemisphere spring equinox is the Southern Hemisphere’s autumnal equinox, so to be understandable to both hemispheres we generally say March or September equinox instead.

Addendum

Sun's path on the equinox for TC-Interlochen

The Sun’s path through the sky on an equinox day from the Traverse City/Interlochen area in Michigan. The Sun is plotted every 15 minutes. This is a stereographic projection which compresses the sky near the zenith and enlarges the sky toward the horizon. Created using my LookingUp program.

03/18/2021 – Ephemeris – The aging Hubble Space Telescope survived its latest glitch

March 18, 2021 Comments off

This is Bob Moler with Ephemeris for Thursday, March 18th. Today the Sun will be up for 12 hours and 4 minutes, setting at 7:53, and it will rise tomorrow at 7:47. The Moon, 3 days before first quarter, will set at 1:21 tomorrow morning.

On Sunday the 7th the Hubble Space Telescope, arguably the most famous telescope there is entered safe mode. Whenever a spacecraft finds an unexpected problem it stops what it is doing, orients itself, so its solar panels face the Sun if it can. It may or may not phone home. And waits for instructions. The last time Hubble experienced a glitch that forced a safe mode was 2018. Then it took 3 weeks to get it back to normal operations. This time it was 4 days. However, the ground controllers are still checking out one of its cameras, while the others are working again. Hubble is over 30 years old. It’s replacement, the James Webb Space Telescope is expected to finally be launched this October on the European Space Agency’s Ariane 5 rocket.

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

Addendum

The Hubble Space Telescope

The Hubble Space Telescope after a servicing mission. Credit: NASA.

Full scale model of the JWST at Goddard Space Flight Center

Full scale model of the James Webb Space Telescope at Goddard Space Flight Center. Note its scale with the people in front of it.

I’ll be covering the James Webb Space Telescope in more detail as we count down to its launch.