Alerts

• Educating first-year students at the University of the Free State
• The Sun, on Christmas Day 2023 — 2023 Dec 26
• Browse the ASSA Solar Bulletins.
• Browse the November 2023 edition of the BAA Solar Section Newsletter.

Visit the Solar Section publications archive for older reports, observations and news.

Welcome to the ASSA Solar Section

The Sun, situated approximately 149 million kilometres away from Earth, is a dynamic variable star. Being the closest star to our planet, it provides a unique opportunity for us to observe and study characteristics that are common among stars throughout the Universe.

The Sun exhibits an 11-year cycle of activity, featuring phenomena such as sunspots, solar flares, prominences, and filaments. Some of these events, such as Coronal Mass Ejections (CMEs), involve the powerful release of plasma and magnetic fields from the Sun’s corona at speeds of thousands of kilometres per hour.

These Solar CMEs can significantly impact Earth’s magnetosphere, potentially causing geomagnetic storms that affect satellites, power grids, communication systems, and even our climate.

Given the scientific importance and recreational interest in tracking these solar activities, the Astronomical Society of Southern Africa (ASSA) Solar Section invites enthusiastic astronomers to participate in solar observations. Members can contribute observations such as sunspot counts and solar images, which are published in our international recognised ASSA solar bulletin.

WARNING: Never look at the Sun without taking proper precautions. Permanent blindness can result from the briefest look through binoculars or a telescope.

To learn more about conducting sunspot observations, please visit the “Observing the Sun”

For those interested in joining and contributing to solar observations, please contact  the Director of the Solar Section. Participants in solar observations will join the ASSA solar observation WhatsApp group, managed by the Solar Section Director

Interesting Facts about the Sun

Age (years)                                         4.5 x 10 ⁵
Mass (kg)                                            1.9891 x 10 ³⁰
Diameter (km)                                   1.392 x 10⁶
Luminosity (Watt)                             3.846 x 10²⁶
Mass conversion rate (kg-s¯¹)         4.3 x 10⁹
Absolute visual magnitude             +4.83
Apparent visual magnitude             -26.74
Core pressure (atmosphere)          2.452 x 10¹¹
Core temperature (⁰C)                     1.571 x 10⁷
Rotation period at equator (days)  26.8
Rotation period at poles (days)      36
Composition (% H, He, other)         71, 27, 2