In this month : March 2023

25th March 1655

Dutch astronomer Christiaan Huygens discovers Titan, the largest moon of Saturn and the second largest natural satellite in the Solar System after Jupiter’s Ganymede. At 5,150 kilometres in diameter Titan is bigger than Earth's moon and larger than the planet Mercury. It is the only moon in the solar system with a dense atmosphere and the only world besides Earth that has bodies of liquid, including rivers, lakes, and seas, on its surface. Titan orbits Saturn once every 15 days and 22 hours at a distance of 1.2 million kilometres from the planet.

Saturn’s moons are named after mythological giants. The name Titan comes from the Titans, a race of immortals in Greek mythology.

Image above:Composite image shows an infrared view of Saturn's moon Titan from NASA's Cassini spacecraft, acquired during the mission's "T-114" flyby on Nov. 13, 2015.

4th March 1979

A photo of a volcanic eruption on Jupiter’s moon Io is taken by the spacecraft Voyager 1 about 12 hours before its closest approach to the planet. This and other photos are the first records of an active volcanic eruption ever observed on another body in the solar system.

The photo, taken from a distance of 499,000 kilometres from the planet, shows a plume-like structure rising more than 100 kilometres above the surface. At least four eruptions were identified in the Voyager 1 pictures and many more may yet be discovered on closer analysis.

Image left : NASA/JPL - the plume is on lower right and the white spot were identified by Linda Morabito as volcanic eruptions.

The fact that several eruptions appear to be going on simultaneously makes Io the most active surface in the solar system and suggests that Io is undergoing continuous volcanism.

1st March 1982

The Russian spacecraft Venera 13 lands in the Phoebe Regio area of Venus and transmits the first recording of actual sounds from another planet. The sounds include the Venusian wind, the lander hitting the ground, pyrotechnic lens cap removal and its impact on regolith, and action of the regolith drilling apparatus.

Although the lander was designed to function for about 32 minutes, it continued to operate for at least 127 minutes in an environment where the temperature was 457 °C and the pressure was 89 standard atmospheres, equivalent to the pressure about 1 kilometre below the surface of the ocean. Exploring the surface of Venus is difficult because of the intense heat and crushing air pressure. This landing is the longest any spacecraft has survived on the surface of Venus. See an image of Venus from Venera 13.

BORN

16th March 1750

Caroline Lucretia Herschel.

German-born British astronomer. She was the younger sister of astronomer William Herschel with whom she worked throughout her career but became a notable astronomer in her own right. Her most significant contributions to astronomy were the discoveries of several comets.

Caroline had many firsts in her career. She was the first woman to receive a salary as a scientist and the first woman in England to hold a government position. She was also the first woman to publish scientific findings in the Philosophical Transactions of the Royal Society. In 1828 she was also the first woman to be awarded a Gold Medal of the Royal Astronomical Society. No woman would receive this award again until Vera Rubin in 1996. She was also the first woman to be made an Honorary Member of the Royal Astronomical Society along with Mary Somerville.

With her brother John she discovered over 2,400 astronomical objects over twenty years.

The asteroid 281 Lucretia was named after Caroline's second given name and the crater C. Herschel on the Moon is named after her.

Caroline Herschel died peacefully in Hanover, Germany on the 9th January 1848 aged 98 years.

Image above: Caroline Herschel's telescope, 1795-1816. Newtonian reflecting telescope with 6 1/8-inch diameter speculum mirror, Royal Astronomical Society. Image courtesy Science Museum, London.

22nd March 1799

Friedrich Wilhelm August Argelander

A German astronomer known for his determinations of stellar brightness, positions, and distances of stars. He was the first astronomer to begin a detailed study of variable stars and was responsible for introducing the modern system of identifying them.

His greatest achievement was the publication of the Bonn Survey, a catalogue of stars from the north celestial pole to 2° south of the celestial equator including all stars down to about ninth magnitude.

The simplicity and ease of using the catalogue have made it one of the most noteworthy aids to astronomy in saving time and work for generations of astronomers. It still maintains a high place in any astronomical observatory today.

The crater Argelander on the Moon and the asteroid 1551 Argelander are named for him.

He died on 17th February 1875.

Image above courtesy University of Helsinki

24th March 1952

Reinhard Genzel.

German astrophysicist. Co-director of the Max Planck Institute for Extraterrestrial Physics and emeritus professor at the University of California, Berkeley, USA. Genzel studies infrared and submillimetre astronomy. He and his research team are active in developing ground and space-based instruments for astronomy which are used to track the motions of stars at the centre of the Milky Way. He is also active in studies of the formation and evolution of galaxies.

In 2020 he was awarded the Nobel Prize in Physics which he shared with Andrea Ghez and Sir Roger Penrose "for the discovery of a supermassive compact object at the centre of our galaxy".

As well as the Nobel prize he is the recipient of many other outstanding awards including the Albert Einstein Medal in 2007 and the Herschel Medal from the Royal Astronomical Society in 2014