Blog – WinStars 3

3d landscapes and photogrammetry

And now, here are some 3D landscapes ! For the moment, this new feature is very experimental. The program only displays a single object (a mesh) containing all the elements of a landscape (vegetation, constructions etc…). These 3D objects have been obtained by photogrammetry, a technique that consists in shooting a scene from a multitude of points of view in order to reconstruct it in volume.

The solar radio telescope element in WinStars.
You can see the complexity of the mesh by activating the 3D/wireframe mode option.

But this solution is not optimal. The details of the landscapes are still too approximate in some cases and the files are far too heavy. I will use later the tessellation technique to improve the quality of the rendering and the size of the modules.

Resuming the development of W3, exoplanets and Artemis 1 mission

After several months of interruption, the development of WinStars is slowly resuming. Among the latest features, we can mention the integration of all known exoplanets that can be easily located from the planetarium mode.

Since the first discoveries of Aleksander Wolszczan and Michel Mayor and Didier Queloz in the 90’s, thousands of exoplanets are now referenced in the catalogs. The space missions Corot, Kepler and Tess have largely contributed to the explosion of their number these last years and the James Webb space telescope is also used to observe them directly. We can mention the example of HIP 65426 b and the first image of an exoplanet obtained in the mid-infrared. It is a very young giant exoplanet, about 15 million years old, located at 90 astronomical units from its star. With an estimated mass of about 7 masses of Jupiter, it had been discovered with the European instrument SPHERE at the Very Large Telescope in 2017.

Images of the exoplanet HIP 65426 b observed by NIRCAM (3.3 and 4.4 microns) and MIRI (11.4 and 15.5 microns). The white star indicates the position of the host star. NASA/STScI/ESA published by Carter and al. 2022

The complete list of exoplanets is accessible from the program by typing the command list exo in the search box. You can also find an object its identifier. The database used by W3 is extracted from the site exoplanet.eu and will be updated every week.

51 Pegasi b was the first exoplanet identified around a main sequence star. It was discovered in 1995 by Michel Mayor and Didier Queloz.

The revision 3.0.268 also proposes to follow the position of the Orion capsule in real time. The objective of this Artemis 1 mission is to return to the moon in 2025 and to maintain a human presence in the long term.

The Orion capsule of the Artemis 1 mission.

The next revisions of W3 will include the ability to visit these exoplanets in the 3D Navigation mode. I also plan to add 3D landscapes in the planetarium mode (for fun) and many other things… But I’ll tell you more about that later.

I continue to improve the stability of the program. It is therefore important to report any malfunctioning to me using the bugtracker or the forums (here and there1). Thank you for your participation!

(1) Many thanks to Sora Kozima for creating this forum on discord.com !

Comets and asteroids in WinStars 3

The latest version of WinStars focuses on comets and asteroids and represents them as faithfully as possible.

To do this, WinStars 3 queries the 3d-asteroids.space database when the user approaches one of these objects and retrieves the corresponding 3D model if one is available.

67P/Churyumov-Gerasimenko as imaged by the Rosetta mission.

Orbiting the Sun, comets and asteroids give us precious information on the components of the planets. Probably having evolved little since their formation 4.6 billion years ago, they appear as remnants of the primordial nebula that formed our solar system. For this reason, these small celestial bodies have attracted the attention of scientists who have developed various techniques for learning more about their physical characteristics (shape, configuration, surface, geology, rotation period, etc.). Some interplanetary missions have, of course, allowed us to approach them (Galileo, NEAR Shoemaker, Dawn or Rosetta), but these missions are far too complex and costly to consider exploring the 390,000 asteroids that have been recorded to date.

The asteroid (1) Ceres seen from the Dawn spacecraft.

Therefore, when one of these objects is located less than two million kilometres from the Earth, it is sometimes possible to use powerful radio telescopes to image its surface and determine its size, morphology, rotation speed and to determine whether or not if it is accompanied by one or more small satellites.

Thus, asteroid 2021 PJ1 was observed on 14 August 2021 with the Deep Space Network’s 70-metre antenna in Barstow, California. And it is with the Arecibo radio telescope that most of the radar imaging studies have been conducted to reach a catalogue of a thousand objects today.

But it is the photometric method of light curves that is most widely used. Asteroids have such small diameters (< 1000 km) that it is impossible to resolve them optically with the largest terrestrial telescopes. However, by observing the variations in the brightness of an asteroid over a period of ten hours or more, it is possible to mathematically reconstruct the geometry of an object and define its period of rotation. These light curves, which show minima and maxima as well as periods, provide indications of an elongated or spherical shape, surface irregularities, the presence of large craters or existence of a companion.

For the time being, only objects with a number < 100 are represented in 3D in the paid version of WinStars 3.

Most asteroids have this rough appearance and are not textured in the software. This means that the light curve method has been used to determine their general shape. A mathematical method that gives no information about the photographic view of the surface.

WinStars 3 is now compatible with the Raspberry Pi computers

The Raspberry Pi is a  small single-board computers developed in the United Kingdom by the Raspberry Pi Foundation in association with Broadcom.

The Raspberry Pi was created to democratise access to computers. Available for less than 40€ in its basic version, it offers several variants of the free GNU/Linux operating system but also works with proprietary OS (Windows 10 IoT Core or Google Android Pi).

The Raspberry 4b board

Ode to Commodore

For a few weeks now, the Raspberry Pi foundation has been offering a version with a keyboard that looks furiously familiar to us.  Taking leaves from the Commodore and ZX Spectrum playbooks, the Pi 400 is a redesigned Raspberry Pi 4 fitted inside a compact keyboard. It is resistant and has a passive cooling system. This can make it an interesting ally during your astronomical observations.

The Raspberry 400

WinStars 3 is now available for free on these little computers. The installation is a little bit complicated but you just need to methodically apply these instructions in a terminal.

The program runs at 20 frames per second on the Raspberry 400 and it is possible to improve performance by overclocking the computer. My Raspberry 400, which runs at 2000Mhz, never goes above 40º.

It is an inexpensive solution to drive a telescope (the Raspberry version offers compatibility with the Indi module) with all the features of the program at hand and, in particular, the gigantic Gaia EDR3 star catalogue which is particularly useful for tracking and making asteroid light curves for example.

Arecibo: the end of a giant

Following two cable breaks last August and November, Arecibo’s radio telescope was in danger and threatened by collapse. The rupture of a third cable finally caused the 900-tonne central platform to fall onto the 305-metre dish.

Arecibo radio telescope

This radio telescope managed by the National Science Foundation, a US government agency, was built in Arecibo on the north coast of the Caribbean island of Puerto Rico. Originally designed to study the ionosphere, it was also an excellent astronomical instrument and the source of many scientific discoveries. On 7 April 1964, shortly after its inauguration, Gordon Pettengill’s team used it to measure the rotation period of Mercury. In August 1989, the observatory was able to capture the image of an asteroid – (4769) Castalia – for the first time in history. The following year, the Polish astronomer Aleksander Wolszczan discovered the PSR pulsar B1257+12, followed in 1992 by its two orbiting planets.

Arecibo was also the data source of the SETI@home project proposed by the Space Science Laboratory of the University of Berkeley. This distributed computing project using computers connected to Internet had two objectives. The first was to prove the effectiveness of this method, which is much less expensive than using supercomputers. The second was to analyse the signals coming from Arecibo’s antenna in order to detect, which was a failure, the existence of non-terrestrial intelligence.

 

It was possible to extract the metadata from the Seti@Home calculation blocks in WinStars versions 1 & 2 and know the celestial coordinates and the frequency that had been used to make the recording from the radio telescope. Version 3 no longer offered this functionality since the project was discontinued in March 2020.

Arecibo was also a filming location. We will remember for example the scene where Jodie Foster discovers for the first time the radio telescope on which she is about to work (Contact by Robert Zemeckis – 1997).

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