05/09/2023 – Ephemeris – The planet Uranus’ rings

This is Ephemeris for Tuesday, May 9th. Today the Sun will be up for 14 hours and 35 minutes, setting at 8:57, and it will rise tomorrow at 6:20. The Moon, 3 days before last quarter, will rise at 1:56 tomorrow morning.

Today, the planet Uranus is in conjunction with the Sun. I don’t talk about Uranus that much, because it can’t be spotted in the sky with the naked eye. However, the James Webb Space Telescope observed it, and gave our clearest view of the planet since Voyager 2 flew past it in January 1986. Uranus has a system of rings, which were discovered in March 1977. Though not visible, they blocked the light of a star. Astronomers at the time were trying to get a more accurate diameter of the planet by timing the disappearance of a star behind the planet. Extra short dips in brightness before and after the main occultation revealed the existence of the rings. Uranus also has an extreme axial tilt of 98 degrees.

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

Uranus and its rings as photographed by the Hubble Space Telescope. Credit NASA/ESA.

Uranus and its rings as photographed by the James Webb Space Telescope. The rings are much brighter in the infrared. Credit: NASA\CSA\ESA.

Closeup of the Uranian rings from Voyager 2. The stars are trailed due to the spacecraft turning to focus on the rings as it moves through the Uranian system in this time exposure. Credit NASA/JPL.

12/26/2022 – Ephemeris – Some space firsts this year

This is Ephemeris for Monday, December 26th. 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, halfway from new to first quarter, will set at 9:10 this evening.

I hope we all survived the holiday season so far. We now have one more to go, New Year’s Eve. The Moon will pass the planet Saturn later this morning. By this evening, Saturn will be to the right of the Moon in the southwestern sky. Now that we’re ending the year, we can look back at some space firsts. The James Webb Space Telescope was launched last Christmas. It became operational late spring of this year and presented its first 5 spectacular images in July. The DART spacecraft, also launched last year, collided with the small asteroid Dimorphos, orbiting the larger Didymos in a 12-hour orbit produced an amazing effect on its orbit. And late this year Artemis I finally launched, making a nearly flawless orbit of the Moon with its Orion space capsule, and returned.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.

Addendum

The Moon and Saturn at 6:30 pm tonight, December 26, 2022. Note that the Moon is shown at twice its apparent size to better show its phase. Created using Stellarium.

The James Webb Space Telescope teaser deep field image from President Biden’s July 11th presentation. Credit: NASA, ESA, CSA, JWST, STScI.

DART images of both Didymos, the big one, and Dimorphos, on approach. Dimorphos is the target. Credit NASA / JHAPL.

Two images from the LiciaCube satellite launched from the DART spacecraft 15 days before the impact, and trailing it to record the collision with its wide and narrow angle imagers. Dimorphos does appear to be a rubble pile asteroid from its appearance and the amount of ejecta caused by the impact. The ejecta adds to the effect of the spacecraft’s kinetic energy by pushing away from the asteroid by Newton’s third law of motion.
Credit Italian Space Agency.

Earthset from Artemis I’s Orion spacecraft, as it moves around to the far side of the Moon. Click on the image to enlarge it. Credit: NASA.

10/04/2022 – Ephemeris – DART does its job, now we wait and watch.

This is Ephemeris for Tuesday, October 4th. Today the Sun will be up for 11 hours and 33 minutes, setting at 7:17, and it will rise tomorrow at 7:45. The Moon, 2 days past first quarter, will set at 2:14 tomorrow morning.

Last week Monday night NASA’s DART spacecraft successfully smashed into the tiny asteroid Dimorphos, which was slowly orbiting an asteroid named Didymos five times its size, and nearly a half mile in size. Dimorphos is too small and too close to Didymos to be seen in optical telescopes. Even the DART spacecraft’s telescope could only spot it in the last hour before the collision. Astronomers have found that they can see asteroid shapes and moonlets by radar. One technique was to send out radar pulses out from the Arecibo Observatory in Puerto Rico and receive them back with the Green Bank Telescope in West Virginia. Now that Arecibo has been destroyed, astronomers transmit from Goldstone, California.

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

Dimorphos collision from as seen from Hubble and JWST. The colors aren’t true. Credit: NASA, ESA, CSA, Jian-Yang Li, Cristina Thomas, Ian Wong, Joseph DePasquale, Alyssa Pagan. From CNET web site.

07/12/2022 – Ephemeris – The rest of the first images and data from the James Webb Space Telescope to be released tomorrow

This is Bob Moler with Ephemeris for Tuesday, July 12th. Today the Sun will be up for 15 hours and 18 minutes, setting at 9:27, and it will rise tomorrow at 6:09. The Moon, 1 day before full, will set at 5:26 tomorrow morning.

Later today at 10:30 am, NASA and the Space Telescope Science Institute will present the first results from the James Webb Space Telescope. These will be, I believe, four multi-spectral images rendered in full color, and other data. The wavelength coverage of Webb in the infrared is greater than Hubble Space Telescope, which is mostly visible light, by several factors. The test images we’ve seen released so far are monochromatic and rendered in white, yellow, orange and red to depict a wide brightness range. There will be a Webb image release with explanations at the Milliken Auditorium of the Dennos Museum at 10:30, with doors opening at 10 am; and also at the Main Library in Traverse City. I’ll endeavor to be at the library.

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

Not known by me last Sunday night when I wrote and recorded today’s program was that President Biden was going to preview one of the images Monday evening. If I were the general public, I would have been underwhelmed. It wasn’t enlarged, or particularly colorful. Here it is below. Click on it for an even larger view:

The teaser deep field image from President Biden’s July 11th presentation. Click on the image to fill your screen with it. Credit: NASA, ESA, CSA, JWST, STScI.

In the image above, anything with diffraction spikes is a star in our galaxy. Everything else is a galaxy, like the Milky Way, with billions of stars. This is a tiny piece of sky. As a rule of thumb, the redder the galaxy, the farther away it is. The light emitted by these galaxies are starlight in mostly visible wavelengths, but shifted to the infrared by their great speed of recession caused by the expansion of space between us and them. Also note that many of these galaxies are distorted into short arcs. They seem curved as if being part of a circle around the large, bright galaxy in the center. This is caused by the gravitational lensing caused by the mass of that galaxy, dark matter, and other galaxies in its cluster. This is an effect predicted by Einstein’s theory of General Relativity. I have a feeling that we are going to see a lot more gravitational lensing as the JWST probes into deeper and deeper fields.

One thing to remember about deep fields, is that because of the speed of light being finite, that the farther we look out, the farther back in time we see into an evolving universe. The farthest back we can see with electromagnetic radiation (that is gamma rays, x-rays, ultraviolet, visible, and infrared light, microwaves and radio waves) is the era of the cosmic microwave background, when the universe became transparent, about 380 thousand years after the Big Bang. After that came a period called the dark ages before galaxies formed and the first stars ignited, called the dark ages. At least that’s what I hear-tell. There are lots of questions, like the chicken and egg question: Which came first, supermassive black holes or galaxies?

We will find answers to some of our questions, I’m sure. Even more intriguing, we will be able to ask even more and deeper questions to probe the mystery and beauty of the universe.

07/11/2022 – Ephemeris – First color images from the James Webb Space Telescope will be released tomorrow

This is Ephemeris for Monday, July 11th. Today the Sun will be up for 15 hours and 20 minutes, setting at 9:28, and it will rise tomorrow at 6:08. The Moon, 2 days before full, will set at 4:19 tomorrow morning.

Tomorrow at 10:30 am, NASA and the Space Telescope Science Institute will present the first results from the James Webb Space Telescope. These will be, I believe, four multi-spectral images rendered in full color, and other data. The spectral range of Webb in the infrared is greater than Hubble Space Telescope by several factors. Hubble operates mostly in visible light and plus a bit in the ultraviolet and the near infrared. The current alignment images released are monochromatic and rendered in orange for aesthetic reasons, and to hint that these are from the long wavelength part of the spectrum. I expect the new images to look as great or better than anything the Hubble has produced. There will be a Webb image release and celebration at the Milliken Auditorium of the Dennos Museum at 10:30, with doors opening at 10 am; and also at the Main Library in Traverse City.

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

The alignment image of the James Webb Space Telescope after the 18 primary mirror segments have been aligned to act as a single mirror. Beside the alignment star showing its overexposed diffraction spikes, many faint galaxies can be seen. The alignment star, near the Big Dipper, is almost too faint to be seen in binoculars. Credit: NASA, Space Telescope Science Institute (STScI).

Webb Fine Guidance Sensor (FGC) test image guiding on a star for 72 exposures totaling 32 hours over 8 days. The color key to brightness is white, yellow, orange, red for bright to dim. The black cores to the stars, and at least one galaxy is due to saturating the pixels due to brightness, and are not black holes. Credits: Canadian Space Agency, NASA, FGS team. The Fine Guidance Sensor is a contribution to the James Webb Space Telescope by the Canadian Space Agency.

12/28/2021 – Ephemeris – The James Webb Telescope is on its way to L2

This is Ephemeris for Tuesday, December 28th. Today the Sun will be up for 8 hours and 50 minutes, setting at 5:09, and it will rise tomorrow at 8:19. The Moon, 2 days past last quarter, will rise at 3:18 tomorrow morning.

The James Webb Space Telescope was launched Christmas morning and is heading out past the Moon’s orbit. It was launched from the European Space Agency’s Spaceport in Kourou, French Guiana on the northeast coast of South America, as part of their contribution to the project. It will orbit a point called Lagrange Point 2, or L2 for short, over four times the Moon’s distance in a direction opposite of the Sun. It will take the telescope 29 days to unfold itself. First order of business was to unfold the solar panels to obtain power, then to deploy its high gain antenna for communications with the Earth. Next to begin to deploy a 5 layer, tennis court sized sun shield. After that, the telescope will be unfolded.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

The last view of Webb as it separated from the Ariane 5 launch vehicle. Credit: NASA.

07/12/11 – Ephemeris – Dim prospects for the James Webb Space Telescope

Tuesday, July 12th.  Today the sun will be up for 15 hours and 18 minutes, setting at 9:27.   The moon, 3 days before full, will set at 4:24 tomorrow morning.  Tomorrow the sun will rise at 6:09.

The US House Appropriation Committee is planning to cancel the Jame Webb Space Telescope.  This follow on to the wildly successful Hubble Space Telescope, is, like its predecessor over budget and behind schedule.  The Webb will gather over 6 times the light as the Hubble, and operate in the infrared where the action is in astronomy now a days.  As it is currently funded the Webb telescope might not be launched by 2018.  They are cutting NASA’s budget by 1.6 billion dollars and want to mandate instead the development of a heavy lift rocket, for which there is no immediate use.  As it is the commercial SpaceX company supposedly can upgrade their current Falcon 9 rocket to a Falcon Heavy quicker and cheaper than NASA can produce their heavy rocket.

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

Addendum

Artist's view of the James Webb Space Tellescope. Courtesy NASA.

Artist's conception of the Falcon Heavy rocket. Courtesy SpaceX.