Friday, January 3, 2025

Welcome to Perihelion


Earth's orbit around the Sun is not a circle, it's an ellipse. The point along its elliptical orbit where our fair planet is closest to the Sun is called perihelion. This year perihelion is today, January 4, at 13:28 UTC, with the Earth about 147 million kilometers from the Sun. For comparison, at aphelion on last July 3 Earth was at its farthest distance from the Sun, some 152 million kilometers away. But distance from the Sun doesn't determine Earth's seasons. It's only by coincidence that the beginning of southern summer (northern winter) on the December solstice - when this H-alpha picture of the active Sun was taken - is within 14 days of Earth's perihelion date. And it's only by coincidence that Earth's perihelion date is within 11 days of the historic perihelion of NASA's Parker Solar Probe. Launched in 2018, the Parker Solar Probe flew within 6.2 million kilometers of the Sun's surface on 2024 December 24, breaking its own record for closest perihelion for a spacecraft from planet Earth.

https://apod.nasa.gov/apod/ap250104.html ( January 04, 2025)

Thursday, January 2, 2025

Eclipse Pair


Eclipses tend to come in pairs. Twice a year, during an eclipse season that lasts about 34 days, Sun, Moon, and Earth can nearly align. Then the full and new phases of the Moon, separated by just over 14 days, create a lunar and a solar eclipse. But only rarely is the alignment at both new moon and full moon phases during a single eclipse season close enough to produce a pair with both total (or a total and an annular) lunar and solar eclipses. More often, partial eclipses are part of any eclipse season. In fact, the last eclipse season of 2024 produced this fortnight-separated eclipse pair: a partial lunar eclipse on 18 September and an annular solar eclipse on 2 October. The time-lapse composite images were captured from Somerset, UK (left) and Rapa Nui planet Earth. The 2025 eclipse seasons will see a total lunar eclipse on 14 March paired with a partial solar eclipse on 29 March, and a total lunar eclipse on 8 September followed by a partial solar eclipse on 21 September.

https://apod.nasa.gov/apod/ap250103.html ( January 03, 2025)

Wednesday, January 1, 2025

Solar Analemma 2024


Recorded during 2024, this year-spanning series of images reveals a pattern in the seasonal drift of the Sun's daily motion through planet Earth's sky. Known to some as an analemma, the figure-eight curve was captured in exposures taken only at 1pm local time on clear days from Kayseri, Turkiye. Of course the Sun's position on the 2024 solstice dates was at the top and bottom of the curve. They correspond to the astronomical beginning of summer and winter in the north. The points along the curve half-way between the solstices, but not the figure-eight curve crossing point, mark the 2024 equinoxes and the start of spring and fall. Regional peaks and dormant volcano Mount Erciyes lie along the southern horizon in the 2024 timelapse skyscape.

https://apod.nasa.gov/apod/ap250102.html ( January 02, 2025)