Jupiter and Saturn: Great conjunction 2020

A Great conjunction is a conjunction of the planets Jupiter and Saturn. Great conjunctions occur regularly (every 19.6 years, on average) due to the combined effect of Jupiter’s approximately 11.86-year orbital period and Saturn’s 29.5-year orbital period and due to the proximity of the orbits of the planets. The upcoming Great conjunction will occur on 21 December 2020.
Conjunctions occur in at least two coordinate systems: equatorial and ecliptic. The conjunctions in first system are measured in right ascension, along the celestial equator. The second system is based on the ecliptic, the plane of the Solar System. When measured along the ecliptic, the separations are usually smaller. Conjunctions are characterized by angular distance between planets and elongation (angular distance from Sun). The visibility of the exact moment of a conjunction depends on the observer’s location.
The upcoming Great conjunction will occur on 21 December at 13:30 UTC (in right ascension). At this time Jupiter will be 0.1 degree (6 arcmins, the one fifth of Moon diameter) south of Saturn and 30.3 degrees east (on the left) of the Sun. The closest approach of the planets will be at 18:25 UTC, elongation at this moment will be 30.1 degree. This Great conjunction will be the closest since 1623. This means that in telescopic field of view, both planets will be visible simultaneously. And also they will be distinguishable from each other without optical aid.
The Great conjunction will occur in the constellation of Capricornus. After sunset, the two planets will be visible at the southwestern part of the horizon, low above it. From mid-northern latitudes, the planets will be less than 15 degrees in altitude, one hour after sunset.
The Great conjunction 2020 in WinStars 3
Check if the Great conjunction 2020 can be seen in your location using WinStars 3.
Source: Wikipedia (redacted version by Sergey Telukhin)

Mars sample return

On July 30, a powerful AtlasV rocket left Earth with the Perseverance rover and the Ingenuity drone on board. The Mars 2020 mission is designed to operate until 2030 and should help NASA and ESA to reach important milestones in the exploration of the Red Planet.

It will begin with a planned landing on February 18, 2021 near the Jezero crater, which presents an interesting profile for the quest of traces of past life. We now know that this crater was a lake several billion years ago.

The rover Perseverance on Mars. Source : NASA/JPL-Caltech

Mars 2020 is in fact the first step in an ambitious project consisting of three missions designed to bring samples back to Earth for further examination. The rover will carry out drilling cores that will be carefully stored before their return to Earth. The Sample Retrieval Lander (SRL), built by NASA, and the Earth Return Orbiter (ERO), developed by the European Space Agency (ESA), are scheduled to launch in a few years to retrieve these precious samples from the Martian soil.

The SRL module, which will also be used for the take-off of the MAV. Source : NASA/JPL-Caltech

You can follow the itinerary of Mars 2020 in W3 by downloading the module of the same name. The trajectory of the probe is directly taken from the Horizons server of the Jet Propulsion Laboratory.

C/2020 F3 (NEOWISE)

C/2020 F3 (NEOWISE) or Comet NEOWISE is a retrograde comet with a near-parabolic orbit discovered on March 27, 2020, by astronomers using the NEOWISE space telescope. At that time, it was a 10th-magnitude comet, located 2 AU (300 million km; 190 million mi) away from the Sun and 1.7 AU (250 million km; 160 million mi) away from Earth.

By July 2020, it was bright enough to be visible to the naked eye. It is one of the brightest comets in the northern hemisphere since Comet Hale–Bopp in 1997. Under dark skies, it can be clearly seen with the naked eye and might remain visible to the naked eye throughout most of July 2020. Until July 23, as the comet gets further from the Sun it will be getting closer to Earth. As of July 16, the comet is about magnitude 2.

For observers in the northern hemisphere, in the morning, the comet appears low above the north-eastern horizon, below Capella. In the evening, the comet can be seen low in the north-western sky. The comet can be seen in the morning and evening because it is circumpolar from about latitude 45N. The evening view is better. On July 17, Comet NEOWISE will enter the constellation of Ursa Major, below the asterism of the Big Dipper (The Plough). (If Ursa Major was upright, it would be on the right of the Big Dipper, as of July 15th.)

C/2020 F3 (NEOWISE). Stack of 10 exposures of 30s each. Star Adventurer mount.

The object was discovered by a team using the NEOWISE space telescope on March 27, 2020. It was classified as a comet on March 31 and named after NEOWISE on April 1. It has the systematic designation C/2020 F3, indicating a non-periodic comet which was the third discovered in the second half of March 2020.

Comet NEOWISE made its closest approach to the Sun (perihelion) on July 3, 2020, at a distance of 0.29 AU (43 million km; 27 million mi). This passage increases the comet’s orbital period from about 4500 years to about 6800 years. Its closest approach to Earth will occur on July 23, 2020, 01:14 UT, at a distance of 0.69 AU (103 million km; 64 million mi) while located in the constellation of Ursa Major.

Seen from Earth, the comet was less than 20 degrees from the Sun between June 11 and July 9, 2020. By June 10, 2020, as the comet was being lost to the glare of the Sun, it was apparent magnitude 7, when it was 0.7 AU (100 million km; 65 million mi) away from Sun and 1.6 AU (240 million km; 150 million mi) away from Earth. When the comet entered the field of view of the SOHO spacecraft’s LASCO C3 instrument on June 22, 2020, the comet had brightened to about magnitude 3, when it was 0.4 AU (60 million km; 37 million mi) away from Sun and 1.4 AU (210 million km; 130 million mi) away from Earth.

By early July, Comet NEOWISE had brightened to magnitude 1, far exceeding the brightness attained by previous comets, C/2020 F8 (SWAN), and C/2019 Y4 (ATLAS). By July, it also had developed a second tail. The first tail is blue and made of gas and ions;. There is also a red separation in the tail caused by high amounts of sodium. The second tail is a golden color and is made of dust, like the tail of Comet Hale–Bopp. This combination resembles comet C/2011 L4 (PANSTARRS). The comet is brighter than C/2011 L4 (PANSTARRS), but not as bright as Hale–Bopp was in 1997. According to the British Astronomical Association, the comet brightened from a magnitude of about 8 at the beginning of June to −2 in early July. This would make it brighter than Hale–Bopp. However, as it was very near to the Sun, it was reported as 0 or +1 magnitude and remained that bright for only a few days. After perihelion, the comet began to fade at about the same rate as it had previously brightened, dropping to magnitude 2.

On July 13, 2020, a sodium tail was confirmed by the Planetary Science Institute’s Input/Output facility. Sodium tails have only been observed in very bright comets like Hale–Bopp and sungrazer C/2012 S1 (ISON).

From the infrared signature Joseph Masiero estimates the diameter of the comet nucleus to be approximately 5 km (3 mi). The nucleus is similar in size to Comet Hyakutake and many short-period comets such as 2P/Encke, 7P/Pons-Winnecke, 8P/Tuttle, 14P/Wolf, and 19P/Borrelly. By July 5, NASA’s Parker Solar Probe had captured an image of the comet, from which astronomers also estimated the diameter of the comet nucleus at approximately 5 km.

To locate the comet in WinStars, use the Search dialog box and type c/2020 f3

Source : Wikipedia

About the Android version

You’re still in containment due to the coronavirus and you don’t know what to do with your days? Test the Android version of WinStars!

I need your help to understand the problems that some users may encounter. So please install the program from Google Play and run it for a few minutes. Then just use the “send a report” function in the main menu to let me collect precious information about this unforgettable experience between your terminal and W3.

If you are very brave, you can also send me your comments and suggestions (what should be changed, added or deleted?). This will help me to propose in the future a version more adapted to the needs of the users.

To reward you for your efforts, five brave beta testers (drawn at random) will receive a free user license to use the full version of WinStars on Windows.

And if you like WinStars and want to support me, please leave a positive comment on the Google Play page of the program.

Thank you for your participation!

Geological map of the Moon

The USGS, the United States Geological Survey, has just published the first geological map of the entire surface of the Moon.

Called “Unified Geologic Map of the Moon”, this highly detailed map could be used for future manned lunar missions. It is based on information collected from the Jaxa’s Kaguya (Selene) probe and the Lunar Reconnaissance Orbiter‘s camera. The map also uses data collected during the various Apollo missions. A publication details the methodology that made this possible.

Map published by USGS with the colour code description
The USGS map in WinStars. To activate it, check the options “Display high resolution textures” and “Show Unified Geologic map of the Moon v2” options in the “Planets/satellites” menu.

WinStars 3.0.128 released

The most important change in this version is the integration of the latest DE438 planetary theory from the Jet Propulsion Laboratory, a research center located in California, whose objective is to prepare automatic exploration missions. The algorithms developed by the scientists model precisely the positions, velocities and accelerations of the main objects of the solar system.

The laboratory proposes files in the form as Chebyshev polynomial coefficients which give with precision the coordinates and speeds but also, more indirectly, quantities such as the orientations of celestial bodies.

The accuracy of the calculations can be tested in WinStars by setting, for example, the date to June 1, 2017 in the solar system mode and by following the Cassini trajectory (Animation function).

The engineers of this mission, which had run out of fuel, chose to precipitate the probe into Saturn’s atmosphere to avoid contamination of one of its satellites by possible staphylococci that could have survived in Cassini for all those years.

But before destroying the probe, it was decided to make 22 dives between the atmosphere and the planet’s rings in a area rich in scientific information.

This release was also an opportunity to review the source code and correct many defects. In the next version, the Android interface will be improved.

Satellite megaconstellations: a threat to astronomy

Starlink is a project of the american company SpaceX that will provide high-speed Internet connection anywhere on the surface of the globe through a myriad of satellites designed for this purpose.

To reduce latency delays, these small satellites weighing less than 260 kg will be placed on low orbits at an altitude of a few hundred kilometres. At term, these satellites will form a fleet of more than 42,000 objects!

This project is a real disaster for astronomers who fear that their work will be seriously affected by these intruders who could parasitize the regions of the sky observed by scientific instruments. This pollution will not only affect deep-sky pictures but could also affect the radiotelescopes that observe the sky in other regions of the electromagnetic spectrum. The exasperation is growing as professional and amateur astronomers notice the first effects of the incessant passing of satellites in the field of view of the instruments.

Detector field of the Blanco telescope of 4 meters diameter installed on Cerro Tololo in Chile. Practically all the sensors of the detector is covered by the light bursts coming from the Starlink satellites during the six-minute exposure that was to be used to search for new dwarf galaxies next to the Large Magellanic Cloud.

But Elon Musk’s company isn’t the only one that wants to use low Earth orbits. OneWeb and Amazon are already working on concurrent projects that will, in a few years, fill the sky with hundreds of thousands of light points impossible to remove.

It will imply the pure and simple transformation of the sky as we know it, making any research in astrophysics impossible from Earth. This is a natural patrimony accessible to all, already well damaged by anarchic peri-urban lighting, which will disappear forever.

Unfortunately, it seems difficult to fight against these huge corporations that decide, in total impunity, to deprive mankind of the spectacle of the night sky. Every month, they obtain authorisation for launching new satellites from organisations such as the International Telecommunication Union or the Federal Communications Commission, using the current legal gap and rules that have become obsolete as a result of this race to space. These  megaconstellations also considerably increase the risk of collisions and could saturate the nearby space with debris of all kinds.

Astronomes can only protest and try to alert public opinion and governments to the dangers of these uncontrollable projects.

To see the extent of the damage, the latest version of WinStars displays the position of the StarLink constellation satellites in real time.

Just go to Solar system objects/satellites menu, use the Update object orbit elements option and select, one by one, all the satellites whose name starts with Starlink.

Starlink satellites in planetarium mode



Tessellation in WinStars

With version 3.0.118, WinStars uses tessellation to improve the rendering of planetary surfaces. This technique, introduced with the OpenGL 4.0 standard, adds a large number of triangles to an object to make its 3D appearance more complex.
Previously, WinStars simulated the relief of a planet by playing with shadows and illusory perspectives. The textures modified by occlusion mapping were then applied on simple geometrical shapes (typically about ten triangles).

Occlusion mapping technique that plays on shadows and lights to simulate roughness on the surface of an object.

Here, wireframe rendering has been activated.  In reality, the surface remains very simple geometrically..

With tessellation, the number of polygons used to represent the details of an object becomes massive. Depressions and bumps are now represented in three dimensions and are no longer simulated.

The significantly more complex surface mesh is visible in wire mode. Triangles are counted here by thousands

The advantage of tessellation lies in the fact that the addition of these new triangles is done internally by the graphics processor during the rendering phase.
Therefore, there is no bandwidth reduction problem between CPU and GPU during this geometric complexification phase. This technique being very optimized, the impact on the fluidity of the software is limited…

This video from Gamers Nexus explains very well the interest of this technique in the video game industry:

Tessellation is enabled for Mars and the Moon and currently only works with desktop versions (Linux, MacOS and Windows). The rendering of the surface of Mars is not as good as for the Moon, the textures quality being much inferior. I’m looking for better textures to offer a comparable rendering.

What’s going on with Betelgeuse ?

Have you noticed that Betelgeuse1, the star forming the right shoulder of the legendary hunter Orion, has recently lost its luster?

The light curves available on the American Association of Variable Star Observers (AAVSO) website confirm a change in magnitude from 0.5 to 1.3 in the space of few weeks. These changes in brightness are not so surprising for this red supergiant, twelve times more massive than our Sun, known for its variability and irregularity. But it is the brutality of this evolution that intrigues astronomers today.

We know that Betelgeuse is the closest candidate for a future supernova explosion in our galaxy. For this reason, it has been observed attentively for the last 50 years with the hope of learning more about the processes at work in the stars’ agony. Even if several scenarios can explain the abnormal decline of its luminosity, we obviously cannot exclude the fact that it is, perhaps, about to explode.

Each time WinStars starts, the program will consult the AAVSO data to reflect the evolution of the magnitude of Betelgeuse. We can already note that the star is not much brighter than its neighbour Bellatrix in the constellation of Orion.

Version 3.0.104 also features a slightly redesigned Animations dialog box. The slider has been replaced by a simple field in which the user can enter a multiplicative factor to speed up, or slow down, the normal rate of time flow.

A new icon will also appear in the right hand menu. It replaces the “point in a direction” icon which was not really needed and was not yet implemented.
It makes it possible to reverse the course of time…

1. The traditional name Betelgeuse is derived from either the Arabic إبط الجوزاء Ibṭ al-Jauzā’, meaning “the armpit of Orion”, or يد الجوزاء Yad al-Jauzā’ “the hand of Orion” (Sources: wikipedia.org)


Apollo 11, processor optimizations and Russian translation

On the occasion of the 50th anniversary of this historic event that captivated the world, the “Apollo 11” module honours the man’s first steps on the Moon.
A 3d model of the LEM and control module is just placed between the Earth and the Moon. No trajectory is calculated. The date is not taken into consideration.

As a coincidence of timing, this new version also offers a Russian translation of the site and software. Thanks to Sergey Telukhin for doing this huge job.

Finally, the Android version contains executables optimized for arm64-v8a and x86 architectures. A specific version for 64-bit x86 processors is in preparation.