Rare comets Lemmon, SWAN visible over Vietnam

Comet SWAN made its closest approach to Earth on Monday at a distance of approximately 39 million kilometers, Space.com reported.

The comet, discovered in September by Ukrainian amateur astronomer Vladimir Bezugly using data from the SOHO-SWAN telescope, may still be visible under ideal conditions using binoculars or a telescope.

Comet Lemmon, discovered in January by the Mount Lemmon Observatory in the United States, is expected to reach its closest point to Earth on Tuesday at a distance of about 89 million kilometers, according to NASA.

Lemmon is projected to reach a magnitude between 3.5 and 4.5, which could make it visible to the naked eye in dark, clear skies.

Astronomers estimate the comet will not return to the inner Solar System for over 1,300 years.

In Vietnam, both comets may be visible from around 6:30 pm to 8:30 pm local time.

Lemmon is expected in the western to northwestern sky near the Ursa Major constellation.

SWAN may appear low in the south-southwestern sky near Aquarius, although visibility will depend on weather, terrain, and light pollution.

Astronomers recommend observing from locations with minimal artificial light.

Visibility may vary as comet brightness can change rapidly due to solar activity and sublimation, when ice turns directly into gas.