January 9 


9 January 1992


Artist's impression of the planets orbiting pulsar PSR B1257+12. Credit: NASA/JPL-Caltech

On January 9, 1992, radio astronomers Aleksander Wolszczan (b. 1946) and Dale Frail (b. 1961) announced the discovery of two planets orbiting the pulsar PSR 1257+12 (also named Lich), the first confirmed discovery of exoplanets. A third planet in the system was confirmed in 1994.

   PSR B1257+12, alternatively designated PSR J1300+1240 or Lich, is a millisecond pulsar, 2,300 light-years (710 parsecs) from the Sun, in the constellation Virgo, rotating at 160.8 times per second (rotation period of 6.2185 milliseconds). It is estimated to have a mass of 1.4 M☉, and the radius of around 10 kilometres, which is typical for most neutron stars and pulsars. The pulsar was discovered by the Polish astronomer Aleksander Wolszczan on February 9, 1990, using the Arecibo radio telescope.

   The pulsar was found to have anomalies in the pulsation period, which led to investigations as to the cause of the irregular pulses. In an article "A planetary system around the millisecond pulsar PSR1257 + 12", published in Nature on January 9, 1992, Wolszczan and Frail announced the discovery of two planets orbiting the pulsar. Using refined methods one more planet was found in 1994. The discovery surprised many astronomers who expected to find planets only around main-sequence stars.

   The pulsar planets:
  • Planet A (PSR B1257+12 b, "Draugr") has a mass of 0.020 ± 0.002 Earth masses (M🜨), semimajor axis 0.19 au and orbital period of 25.262 days. It is the lowest-mass planet yet discovered by any observational technique.
  • Planet B (PSR B1257+12 c, "Poltergeist"): mass 4.3 ± 0.2 M🜨, semimajor axis 0.36 au, orbital period 66.5419 days.
  • Planet C (PSR B1257+12 d, "Phobetor"): mass 3.9 ± 0.2 M🜨, semimajor axis 0.46 au, orbital period 98.2114 days.
Aleksander Wolszczan


Dale Frail


© 2026, Andrew Mirecki



9 January 2024


Artist's impression of the Einstein Probe

Einstein Probe (Aiyinsitan Tanzhen), a wide-field x-ray space observatory designed to detect flashes caused by cataclysmic cosmic events, was launched by a Long March 2C rocket from the Xichang Satellite Launch Centre in China, on January 9, 2024. The mission is led by the Chinese Academy of Sciences in collaboration with the European Space Agency (ESA) and the Max Planck Institute for Extraterrestrial Physics.

The observatory has two science instruments:

1. Wide-field X-ray Telescope (WXT) — provides a large field of view and uses novel lobster-eye optics to observe a large portion of the sky at any give time,

2. Follow-up X-ray Telescope (FXT) — homes in on X-ray sources found with WXT with a much higher resolution and larger light-collecting power.

The primary scientific objectives are: 

1. Discover and characterize cosmic X-ray transients, to reveal their properties and gain insight into their nature and underlying physics.
2. Discover and characterize X-ray outbursts from normally quiescent black holes, for better understanding of the demography of black holes and their origin and evolution, as well as accretion physics.
3. Search for X-ray sources associated with gravitational-wave events and precisely locate them.


© 2026, Andrew Mirecki

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