India Maps Sun’s Rotation with New Data

Indian Astronomers Map Sun’s Rotation: 100-Year Data from Kodaikanal Observatory

Indian astronomers have achieved a groundbreaking feat. They have mapped, for the first time, the variation in the Sun’s rotation speed. This work was made possible through 100 years of daily solar observations from the Kodaikanal Solar Observatory. This study provides new insights into the Sun’s chromosphere, which is crucial for predicting solar activity and its impact on Earth.

The Sun’s rotation differs significantly from that of Earth. While Earth rotates uniformly, different parts of the Sun rotate at varying speeds. For instance, the Sun’s equator completes one full rotation in about 25 days, while its poles take about 35 days. This differential rotation plays a vital role in driving the Sun’s magnetic activity, which can lead to solar storms that affect technology on Earth.

Previous methods of measuring the Sun’s rotation relied on sunspots, which are dark patches caused by intense magnetic activity on the Sun’s surface. However, sunspots are limited to lower latitudes, making it challenging to study higher latitudes. To overcome this, researchers at the Indian Institute of Astrophysics (IIA) used solar plages and network features—bright regions in the chromosphere—to map the Sun’s rotation at higher latitudes.

Plages are larger and brighter than sunspots, remaining visible throughout the solar cycle, making them ideal for long-term observation. These features, along with network cells, allowed scientists to measure the Sun’s rotation even at the poles.

Their analysis revealed that the Sun’s rotation is fastest at the equator (13.98 degrees per day) and slows down towards the poles (10.5 degrees per day at 80 degrees latitude). This study marks the first time chromospheric network cells have been used to map the Sun’s rotation across latitudes.

The findings, published in the Astrophysical Journal, provide critical insights into the Sun’s magnetic field and its activity cycles.