Jun 262018
 

Today is the birthday (1730) of Charles Messier FRS, a French astronomer most notable for publishing an astronomical catalogue consisting of nebulae and star clusters that came to be known as the 110 Messier objects. The purpose of the catalogue was to help astronomical observers, in particular comet hunters such as himself, distinguish between permanent and transient visually diffuse objects in the sky.

Messier was born in Badonviller in Lorraine, the 10th of 12 children of Françoise B. Grandblaise and Nicolas Messier, a Court usher. Six of his brothers and sisters died while young and in 1741, his father died. Charles’s interest in astronomy was stimulated by the appearance of the spectacular, great six-tailed comet in 1744 and by an annular solar eclipse visible from his hometown on 25th July 1748. In 1751 Messier began working for Joseph Nicolas Delisle, the astronomer of the French Navy, who instructed him on how to keep careful records of his observations. Messier’s first documented observation was that of the Mercury transit of 6th May 1753, followed by his observations journals at Cluny Hotel and at the French Navy observatories. In 1764, he was made a fellow of the Royal Society, in 1769, he was elected a foreign member of the Royal Swedish Academy of Sciences, and in 1770 he was elected to the French Academy of Sciences.

Messier discovered 13 comets, and in the process compiled what is now called the Messier Catalogue. Messier’s occupation as a comet hunter led him to continually come across fixed diffuse objects in the night sky which could be mistaken for comets. He compiled a list of them, in collaboration with his friend and assistant Pierre Méchain (who may have found at least 20 of the objects), to avoid wasting time sorting them out from the comets they were looking for. The entries are now known to be galaxies (39), planetary nebulae (5), other types of nebulae (7), and star clusters (55).

Messier did his observing with a 100 mm (4 inch) refracting telescope from Hôtel de Cluny (now the Musée national du Moyen Âge), in Paris. The list he compiled contains only objects found in the area of the sky he could observe, from the north celestial pole to a declination of about −35.7°. They are not organized scientifically by object type, or even by location. The first version of Messier’s catalogue contained 45 objects and was published in 1774 in the journal of the French Academy of Sciences in Paris. In addition to his own discoveries, this version included objects previously observed by other astronomers, with only 17 of the 45 objects being Messier’s By 1780 the catalog had increased to 80 objects.

The final version of the catalogue was published in 1781, in the 1784 issue of Connaissance des Temps. The final list of Messier objects had grown to 103. On several occasions between 1921 and 1966, astronomers and historians discovered evidence of another seven objects that were observed either by Messier or by Méchain, shortly after the final version was published. These seven objects, M104 through M110, are accepted by astronomers as “official” Messier objects. The objects’ Messier designations, from M1 to M110, are still used by professional and amateur astronomers today and their relative brightness makes them popular objects in the amateur astronomical community.

Near the end of his life, Messier self-published a booklet connecting the appearance of the great comet of 1769 to the birth of Napoleon, who was in power at the time of publishing. I don’t know what came of it, but it was a generally servile and opportunistic tract praising the epoch of “Napoleon the Great” which, in fact, was coming to an end at the time. I don’t know what he hoped to gain by this crass move, but Napoleon had his hands full at the time, and certainly did not have time for a fawning astronomer’s praise when Europe was attacking him from all sides.

Messier died in April 1817 and is buried in Père Lachaise Cemetery, Paris, in Section 11. The grave is plain and faintly inscribed, and while it is not on most maps of the cemetery, it can be found near the grave of Frédéric Chopin.

I have given recipes for several classic dishes from Messier’s native Lorraine, and no doubt will have occasion to do so in the future. The region gave birth to numerous influential people. Today I will give you potée Lorraine, a stew of pork with cabbage, beans, and root vegetables. Some cooks use local sausage in place of (or in addition to) bacon, and leeks in place of onions; some omit the beans. This is one of those “stick stuff in a pot and cook a long time” stews, so you can more or less do as you please, but the ingredients I give here work well together. It’s typical to make large quantities of the dish and serve it over several days. It will get richer when kept overnight in the refrigerator and reheated the next day. Some cooks make a dipping sauce of heavy cream, shallots, vinegar and whole grain mustard. This adds an extra twist.

Potée Lorraine

Ingredients

6 bacon slices, chopped
3 lb boneless pork shoulder, cut into cubes
2 medium onions, peeled and chopped
4 cups chicken broth
2 cups beef broth
1 cup dry white wine
2 bay leaves
1 ½ lb cabbage, chopped
3 large carrots, peeled and diced
2 turnips, peeled and diced
2 russet potatoes, peeled and diced
1 ½ lb cooked white kidney beans
1 tsp ground cloves (or to taste)
1 lb green beans, trimmed, cut into 1 ½ inch lengths, and poached lightly

Instructions

Cook the bacon in heavy 8-quart stock pot over medium heat to render the fat. Take your time, and watch carefully, so that as much fat as possible is rendered, but the lean meat remains. Using slotted spoon, transfer the bacon to a bowl. Pour off all but 2 tablespoons of fat from the pot and reserve.

Heat the fat in the pot over high heat and, working in batches brown the pork on all sides. Transfer each batch to the bowl with the bacon when it is browned. When the pork is all browned and reserved, reduce the heat to medium, add the onions to the pot, and cook them until they are soft and translucent.

Return the pork and bacon to the pot, add the chicken and beef broth, wine cloves, and bay leaves, bring to a simmer, cover, and cook for 1 hour.

Heat the reserved bacon fat in a heavy skillet over medium-high heat. Add the cabbage and cook until wilted. Add the carrots, turnips and potatoes and continue to cook, stirring often for about 5 minutes. Add the vegetables to the pot with the pork. Cover and simmer for another 45 minutes, or until the pork is tender.

Add the kidney beans to the pot. Simmer uncovered for about 15 minutes, so that the liquid reduces and thickens. Taste and adjust the seasoning as needed. Add the green beans and let them heat though for a few minutes.

Some cooks serve the broth first and then the meat and vegetables, some serve everything at once in shallow bowls.

Feb 252018
 

Today is the birthday (1670) of Maria Margaretha Kirch (née Winckelmann), a Saxon astronomer, and one of the most famous astronomers of her time due to her observations of the conjunction of the sun with Saturn, Venus, and Jupiter. She was also the first woman astronomer to discover a comet. Maria Kirch could well serve as the poster child of what women in the 17th and 18th centuries had to endure to be recognized as competent scientists.

Kirch, was born in Panitzsch, near Leipzig, and educated from an early age by her father, a Lutheran minister, who believed that she deserved an education equivalent to that given to young boys of the time. By the age of 13 she was an orphan, but she had received a general education from her brother-in-law Justinus Toellner and the well-known astronomer Christoph Arnold, who lived nearby. Her education was continued by her uncle. She continued studying with Arnold, a self-taught astronomer who worked as a farmer in Sommerfeld, near Leipzig. She became Arnold’s unofficial apprentice and later his assistant, living with him and his family.

Through Arnold, Maria met the famous German astronomer and mathematician Gottfried Kirch, who was 30 years her senior. They married in 1692, later having four children, all of whom followed in their parents’ footsteps by studying astronomy. In 1700 the couple moved to Berlin, because the elector/ruler of Brandenburg, Frederick III, later Frederick I of Prussia, had appointed Gottfried Kirch as his royal astronomer.

Gottfried Kirch gave his wife further instruction in astronomy, as he did for his sister and many other students. Women were not allowed to attend universities in Germany, but the actual work of astronomy, and the observation of the heavens, took place largely outside the universities. Thus Kirch became one of the few women active in astronomy in the early 18th century. She became widely known as Maria Kirchin, the feminine version of the family name. It was not unheard of in the Holy Roman Empire for a woman to be active in astronomy at the time. Maria Cunitz, Elisabeth Hevelius and Maria Clara Eimmart had been active astronomers in the 17th century.

Through an edict, Friedrich III introduced a monopoly for calendars in Brandenburg, and later Prussia, imposing a calendar tax. The income from this monopoly was to pay astronomers and members of the Berlin Academy of Sciences which Friedrich III founded in July 1700. Friedrich III also went on to build an observatory, which was inaugurated in January 1711. Assisted by his wife, Gottfried Kirch prepared the first calendar of a series, entitled Chur-Brandenburgischer Verbesserter Calender Auff das Jahr Christi 1701, which became very popular. Calendars and almanacs were popular, not only because they indicated the dates for Easter and related movable celebrations, but also because they gave astronomical information, as well as general knowledge concerning science and other matters.

Maria and Gottfried worked together as a team. She moved on from her position as Arnold’s apprentice, to become assistant to her husband. Her husband had studied astronomy at the University of Jena and had served as apprentice to Johannes Hevelius. At the academy she worked as his unofficial, but acknowledged, assistant. Women’s positions in the sciences was akin to their position in the guilds, valued but subordinate. Together they made observations and performed calculations to produce calendars and ephemerides. From 1697, the Kirchs also began recording weather information. The data collected by the Kirchs was not only used to produce calendars and almanacs, but was also useful for navigation. The academy in Berlin handled sales of their calendars.

During the first decade of her work at the academy as her husband’s unofficial assistant, Kirch observed the heavens, every evening starting at 9pm. During such a routine observation on 21st April 1702 she discovered the so-called “Comet of 1702” (C/1702 H1). In his notes from that night her husband recorded:

Early in the morning (about 2:00 am) the sky was clear and starry. Some nights before, I had observed a variable star and my wife (as I slept) wanted to find and see it for herself. In so doing, she found a comet in the sky. At which time she woke me, and I found that it was indeed a comet. I was surprised that I had not seen it the night before.

Germany’s only scientific journal at the time Acta eruditorum was in Latin. Kirch’s subsequent publications in her own name were all in German. At the time her husband did not hold an independent chair at the academy and the Kirchs worked as a team on common problems. The couple observed the heavens together, he observed the north and she the south. Kirch’s publications, which included her observations on the Aurora Borealis (1707), the pamphlet “Von der Conjunction der Sonne des Saturni und der Venus” (on the conjunction of the sun with Saturn and Venus) (1709), and the approaching conjunction of Jupiter and Saturn in 1712 became her lasting contributions to astronomy. Before her, the only women astronomer in the Holy Roman Empire that had published under her own name had been Maria Cunitz. The family friend and vice-president of the academy, Alphonse des Vignoles said in Kirch’s eulogy: “If one considers the reputations of Frau Kirch and Frau Cunitz, one must admit that there is no branch of science… in which women are not capable of achievement, and that in astronomy, in particular, Germany takes the prize above all other states in Europe.”

In 1709 academy president Gottfried von Leibniz presented her to the Prussian court, where Kirch explained her sightings of sunspots. He said about her:

She is a most learned woman who could pass as a rarity. Her achievement is not in literature or rhetoric but in the most profound doctrines of astronomy. I do not believe that this woman easily finds her equal in the science in which she excels. She favors the Copernican system, like all the learned astronomers of our time. And it is a pleasure to hear her defend that system through the Holy Scripture in which she is also very learned. She observes with the best observers and knowns how to handle marvelously the quadrant and the telescope.

After her husband died in 1710, Kirch attempted to assume his place as astronomer and calendar maker at the Royal Academy of Sciences. Despite her petition being supported by Leibniz, the president of the academy and the executive council of the academy rejected her request for a formal position saying that “what we concede to her could serve as an example in the future.” God forbid that appointing a woman would set a precedent !! In her petition Kirch set out her qualifications for the position. She argued that she was well qualified because she had been instructed by her husband in astronomical calculation and observation. She emphasized that she had engaged in astronomical work since her marriage and had worked at the academy since her husband’s appointment 10 years earlier. In her petition Kirch said that “for some time, while my dear departed husband was weak and ill, I prepared the calendar from his calculations and published it under his name”. For Kirch an appointment at the academy would have not been just a mark of honour, but was vital in securing an income for herself and her children. In her petition she said that her husband had not left her with means of support. The guild tradition of the time did establish a legitimate claim for Kirch to take over her husband’s position after his death. But these traditions were not followed by the new institutions of science.

While Kirch had carried out important work at the academy, she did not have a university degree, which at that time nearly every member of the academy had. But the academy secretary Johann Theodor Jablonski also cautioned Leibniz,

. . . that she be kept on in an official capacity to work on the calendar or to continue with observations simply will not do. Already during her husband’s lifetime the academy was burdened with ridicule because its calendar was prepared by a woman. If she were now to be kept on in such a capacity, mouths would gape even wider.

Leibniz was the only member of the academy council who supported her appointment. In one of the last council meetings he presided over before leaving Berlin in 1711 Leibniz tried to secure financial assistance for Kirch. Kirch was of the opinion that her petitions were denied due to her gender. This position is supported by the fact that Johann Heinrich Hoffmann, who had little experience, was appointed to her husband’s place instead of her. Hoffmann soon fell behind with his work and failed to make required observations. It was even suggested that Kirch become his assistant. Kirch wrote “Now I go through a severe desert, and because… water is scarce… the taste is bitter”. However, she was admitted by the Berlin Academy of Sciences.

In 1711, she published “Die Vorbereitung zug grossen Opposition,” a well-received pamphlet in which she predicted a new comet, followed by a pamphlet concerning Jupiter and Saturn. In 1712 Kirch accepted the patronage of Bernhard Friedrich von Krosigk, who was an enthusiastic amateur astronomer, and began work in his observatory. She and her husband had worked at Krosigk’s observatory while the academy observatory was being built. At Krosigk’s observatory she reached the rank of master astronomer.

After Baron von Krosigk died in 1714 Kirch moved to Danzig to assist a professor of mathematics for a short time before returning. In 1716 Kirch and her son, who had just finished university, received an offer to work as astronomers for the Russian czar Peter the Great, but preferred to remain in Berlin where she continued to calculate calendars for locales such as Nuremberg, Dresden, Breslau, and Hungary.

Kirch had trained her son Christfried Kirch and daughters Christine Kirch and Margaretha Kirch to act as her assistants in the family’s astronomical work, continuing the production of calendars and almanacs as well as making observations. In 1716 her son Christfried and Johann Wilhelm Wagner were appointed observers at the academy observatory following Hoffmann’s death. Kirch moved back to Berlin to act as her son’s assistant together with her daughter Christine. She was once again working at the academy observatory calculating calendars. Academy members complained that she took too prominent a role and was too visible at the observatory when strangers visit. Kirch was ordered to “retire to the background and leave the talking to… her son.” She refused to comply and was forced by the academy to give up her house on the observatory grounds.

Kirch continued working in private and died of a fever in Berlin on the 29th December 1720.

Kirch’s home town, Leipzig, is famous for many dishes including Leipziger Allerei (Leipzig Hodgepodge). It is basically a vegetable stew enriched with crayfish and butter. The latter are often omitted in modern versions. Here is a traditional version.

Leipziger Allerei

Ingredients

9 oz/250 g carrots
9 oz/250 g kohlrabi
9 oz/250 g asparagus
9 oz/250 g cauliflower
9 oz/250 g morels
18 oz/500 g fresh peas in pods
vegetable broth
4 crayfish
10 tbsp/150 g butter at room temperature
3 eggs
⅛ tsp nutmeg (or mace)
dried bread crumbs
1.7 oz/50 g flour
milk
salt and pepper

Instructions

Clean and peel the carrots and kohlrabi and cut them evenly into long strips. Shell the peas. Cook these three vegetables together in salted water until they are barely al dente.

Peel the white asparagus, cut the spears into pieces about 2”(5 cm) long. Simmer them in a light vegetable broth.

Cut the cauliflower into florets and cook in milk, adding butter and salt to taste.

Cut the morels into halves and sauté in butter.

Boil the crayfish, and split into pieces, carefully removing the meat from the tails. Rub the head of the crayfish with salt.

Whisk about 2 ounces of the butter until light. Separate the eggs. Beat the egg whites until foamy. Fold the egg yolks, egg whites, mace and breadcrumbs into the whisked butter and fill the crayfish head with this mixture. Form the remaining mixture into dumplings and cook these in boiling salt water for 5 minutes.

Put about 3½ ounces of the butter and the flour in a skillet over medium-low heat to make a roux, stirring constantly.  Add a little of the asparagus and cauliflower water, and whisk to make a thick sauce.

Brown the remainder of the butter over medium heat in a small pan, and set it aside.

Place the mixed vegetables, except the morels, into a serving bowl. Add some of the roux sauce, then the crayfish tails and dumplings, sprinkle with browned butter, and add the morels, crayfish legs and heads. Pour the sauce over it. Then add the dumplings and crayfish tails. Drizzle everything with brown butter, and arrange the morels, and crayfish heads and claws on top.

Nov 122017
 

On this date in 2014 the lander module Philae detached from the Rosetta space probe built by the European Space Agency and landed on comet Churyumov–Gerasimenko (a.k.a. 67P) at 15:33 UTC.

Rosetta was set to be launched on 12 January 2003 to rendezvous with the comet 46P/Wirtanen in 2011. This plan was abandoned after the failure of an Ariane 5 carrier rocket during Hot Bird 7’s launch on 11 December 2002, grounding it until the cause of the failure could be determined. In May 2003, a new plan was formed to target the comet 67P/Churyumov–Gerasimenko, with a revised launch date of 26 February 2004 and comet rendezvous in 2014. The larger mass and the resulting increased impact velocity made modification of the landing gear necessary.

After two scrubbed launch attempts, Rosetta was launched on 2 March 2004 at 07:17 UTC from the Guiana Space Centre in French Guiana. Aside from the changes made to launch time and target, the mission profile remained almost identical. Both co-discoverers of the comet, Klim Churyumov and Svetlana Gerasimenko, were present at the spaceport during the launch.

To achieve the required velocity to rendezvous with 67P, Rosetta used gravity assist maneuvers to accelerate throughout the inner Solar System. The comet’s orbit was known before Rosetta’s launch, from ground-based measurements, to an accuracy of approximately 100 km (62 mi). Information gathered by the onboard cameras beginning at a distance of 24 million kilometers (15,000,000 mi) were processed at ESA’s Operation Centre to refine the position of the comet in its orbit to a few kilometres.

On 25 February 2007, the craft was scheduled for a low-altitude flyby of Mars, to correct the trajectory. This was not without risk, as the estimated altitude of the flyby was a mere 250 kilometers (160 mi). During that encounter, the solar panels could not be used since the craft was in the planet’s shadow, where it would not receive any solar light for 15 minutes, causing a dangerous shortage of power. The craft was therefore put into standby mode, with no possibility to communicate, flying on batteries that were originally not designed for this task. This Mars maneuver was therefore nicknamed “The Billion Euro Gamble”. The flyby was successful, with Rosetta even returning detailed images of the surface and atmosphere of the planet, and the mission continued as planned.

The second Earth flyby was on 13 November 2007 at a distance of 5,700 km (3,500 mi).] In observations made on 7 and 8 November, Rosetta was briefly mistaken for a near-Earth asteroid about 20 m (66 ft) in diameter by an astronomer of the Catalina Sky Survey and was given the provisional designation 2007 VN84. Calculations showed that it would pass very close to Earth, which led to speculation that it could impact Earth.[73] However, astronomer Denis Denisenko recognized that the trajectory matched that of Rosetta, which the Minor Planet Center confirmed in an editorial release on 9 November.

The spacecraft performed a close flyby of asteroid 2867 Šteins on 5 September 2008. Its onboard cameras were used to fine-tune the trajectory, achieving a minimum separation of less than 800 km (500 mi). Onboard instruments measured the asteroid from 4 August to 10 September. Maximum relative speed between the two objects during the flyby was 8.6 km/s (19,000 mph; 31,000 km/h). Rosetta’s third and final flyby of Earth happened on 12 November 2009.

On 10 July 2010, Rosetta flew by 21 Lutetia, a large main-belt asteroid, at a minimum distance of 3,168±7.5 km (1,969±4.7 mi) at a velocity of 15 kilometers per second (9.3 mi/s). The flyby provided images of up to 60 meters (200 ft) per pixel resolution and covered about 50% of the surface, mostly in the northern hemisphere. The 462 images were obtained in 21 narrow- and broad-band filters extending from 0.24 to 1 μm. Lutetia was also observed by the visible–near-infrared imaging spectrometer VIRTIS, and measurements of the magnetic field and plasma environment were taken as well.

In May 2014, Rosetta began a series of eight burns. These reduced the relative velocity between the spacecraft and 67P from 775 m/s (2,540 ft/s) to 7.9 m/s (26 ft/s). In 2006, Rosetta suffered a leak in its reaction control system (RCS). The system, which consists of 24 bipropellant 10-newton thrusters, was responsible for fine tuning the trajectory of Rosetta throughout its journey. The RCS operated at a lower pressure than designed due to the leak. While this may have caused the propellants to mix incompletely and burn ‘dirtier’ and less efficiently, ESA engineers were confident that the spacecraft would have sufficient fuel reserves to allow for the successful completion of the mission.

Rosetta’s reaction wheels also showed higher than expected friction levels, though testing during the deep space hibernation period revealed the system could be operated safety at much slower speeds reducing the bearing friction noise. Before hibernation, two of the spacecraft’s four reaction wheels began exhibiting increased levels of “bearing friction noise” and one was turned off after the encounter with Lutetia to avoid possible failure. Engineers turned on all 4 wheels after the spacecraft awoke from Deep Space Hibernation in January 2014, ran them at lower speeds and elevated the control settings on the bearing heaters using an On-board Control Procedure to help reduce the level of bearing friction noise seen on 2 of the Reactions Wheels prior to Deep Space HIbernation. These changes allowed all 4 Reaction Wheels to be used throughout the period Rosetta was in orbit around 67P/Churyumov–Gerasimenko. Additionally, new software was uploaded which would allow Rosetta to function with only two active reaction wheels if necessary.

In August 2014, Rosetta made a rendezvous with the comet 67P/Churyumov–Gerasimenko and commenced a series of maneuvers that took it on two successive triangular paths, averaging 100 and 50 kilometers (62 and 31 mi) from the nucleus, whose segments are hyperbolic escape trajectories alternating with thruster burns. After closing to within about 30 km (19 mi) from the comet on 10 September, the spacecraft entered actual orbit about it.

The surface layout of 67P was unknown before Rosetta’s arrival. The orbiter mapped the comet in anticipation of detaching its lander. By 25 August 2014, five potential landing sites had been determined. On 15 September 2014, ESA announced Site J, named Agilkia in honour of Agilkia Island by an ESA public contest and located on the “head” of the comet, as the lander’s destination.

Philae detached from Rosetta on 12 November 2014 at 08:35 UTC, and approached 67P at a relative speed of about 1 m/s (3.6 km/h; 2.2 mph). It initially landed on 67P at 15:33 UTC, but bounced twice, coming to rest at 17:33 UTC. Confirmation of contact with 67P reached Earth at 16:03 UTC. On contact with the surface, two harpoons were to be fired into the comet to prevent the lander from bouncing off, as the comet’s escape velocity is only around 1 m/s (3.6 km/h; 2.2 mph). Analysis of telemetry indicated that the surface at the initial touchdown site is relatively soft, covered with a layer of granular material about 0.82 feet (0.25 meters) deep, and that the harpoons had not fired upon landing.

After landing on the comet, Philae had been scheduled to commence its science mission, which included:

Characterization of the nucleus

Determination of the chemical compounds present, including amino acid enantiomers

Study of comet activities and developments over time

After bouncing, Philae settled in the shadow of a cliff, canted at an angle of around 30 degrees. This made it unable to adequately collect solar power, and it lost contact with Rosetta when its batteries ran out after two days, well before much of the planned science objectives could be attempted. Contact was briefly and intermittently reestablished several months later at various times between 13 June and 9 July, before contact was lost once again. There was no communication afterwards, and the transmitter to communicate with Philae was switched off in July 2016 to reduce power consumption of the probe. The precise location of the lander was discovered in September 2016 when Rosetta came closer to the comet and took high-resolution pictures of its surface. Knowing its exact location provides information needed to put Philae’s two days of science into proper context.

Researchers expect the study of data gathered will continue for decades to come. One of the first discoveries was that the magnetic field of 67P oscillated at 40–50 millihertz. A German composer and sound designer created an artistic rendition from the measured data to make it audible. Although it is a natural phenomenon, it has been described as a “song” and has been compared to Continuum for harpsichord by György Ligeti. However, results from Philae’s landing show that the comet’s nucleus has no magnetic field, and that the field originally detected by Rosetta is likely caused by the solar wind.

The isotopic signature of water vapor from comet 67P, as determined by the Rosetta spacecraft, is substantially different from that found on Earth. That is, the ratio of deuterium to hydrogen in the water from the comet was determined to be three times that found for terrestrial water. This makes it very unlikely that water found on Earth came from comets such as comet 67P, according to the scientists. On 22 January 2015, NASA reported that, between June and August 2014, the rate at which water vapor was released by the comet increased up to tenfold.

On 2 June 2015, NASA reported that the ALICE spectrograph on Rosetta determined that electrons within 1 km (0.6 mi) above the comet nucleus — produced from photoionization of water molecules by solar radiation, and not photons from the Sun as thought earlier — are responsible for the degradation of water and carbon dioxide molecules released from the comet nucleus into its coma.

I don’t have any great ideas for food recipes to celebrate a module landing on a comet, but I do have two ideas for recipes in a wider sense. Once is a “recipe” for making a comet, or a simulacrum of a comet made out of common items, most of which are available in the kitchen. If you go on YouTube and search for “comet recipe” you will find any number of videos of people replicating the structure of comets using household items.  Here’s one:

That recipe does not produce something edible, however. On the other hand, there are quite a few recipes for cocktails called “comet.” They are all quite different from one another, and none, in my opinion, evokes comets in any way. I don’t drink alcohol any more, but when I did I had some memorable experiences with blackcurrant vodka, so this one struck a chord:

Comet Cocktail

Ingredients

30ml Smirnoff Double Black vodka
10ml blackcurrant cordial
60ml pineapple juice
lemon wedge

Instructions

Shake the vodka, blackcurrant cordial, and pineapple juice in a cocktails shaker.  Pour over cracked ice in a glass and garnish with a lemon wedge.