Category: Sky Events
Sky events
Mercury at Maximum Elongation
Today Mercury will be at maximum western elongation, as high in the morning sky as it will appear for this current apparition. After today the planet will slide back into the dawn, passing through superior conjunction on April 9th to reappear in the evening sky around the end of April.
Mercury Appears in the Dawn
The planet Mercury is starting a morning apparition. The planet should become visible this week just above the dawn as a magnitude -1 object. The planet is moving more than 1° further from the Sun and higher in the morning sky each day, reaching a maximum elongation of 27° on February 24th. This will be the best morning apparition for Mercury in 2015.
Full Moon
Mercury at Inferior Conjunction
Today the planet Mercury passes through inferior conjunction, passing between the Sun and the Earth. In a week or so the planet will again be visible in the dawn sky, climbing higher each day. Maximum elongation will occur February 24th.
Mercury at Maximum Elongation
Today Mercury will be at maximum eastern elongation, as high in the evening sky as it will appear for this current apparition. After today the planet will slide back into the sunset, passing through inferior conjunction on January 30th and reappearing in the dawn during the first weeks of February.
Mercury and Venus
Mercury and Venus will be in a close conjunction this evening. While the pair has been drawing closer for the last week, tonight will see them at their closest, about 38′ separation.
Look for the bright planet Venus low in the sunset. Mercury will slightly down and to the north of Venus. A separation of 38′ is just a bit more that the width of the full Moon. Both objects are fairly bright, with Venus shining at -3.9 magnitude and Mercury at -0.7. Bright enough to be quite obvious, the pair will be 17° above the horizon at sunset.
Over the coming week the pair will slightly separate. Mercury will be at maximum elongation on January 14th, after which it will begin its slide back into the sunset.
Mercury and Venus
Over the next week Mercury and Venus will rendezvous in the sunset. This evening will see the two separated by 48′, well under one degree. This will close to about 38′ on the evening of January 10th, just a little over the width of a full Moon apart. Both objects are fairly bright, with Venus shining at -3.9 magnitude and Mercury at -0.7. Bright enough to be quite obvious, the pair will be 17° above the horizon at sunset.
Full Moon
Earth at Perihelion
Today the Earth is closest to the Sun, a point called perihelion. We will be about 147,099,000km (91,403,000miles) from the Sun. Compare this to the 152,096,000km (94,508,000miles) we will be at aphelion on July 6th, a difference of about 4,996,000km (3,104,000miles) occurs throughout one orbit.
It may seem odd that we are actually at the closest for the middle of northern winter, you just have to remember that proximity to the Sun is not the cause of the seasons. The seasons are caused by the axial tilt of the Earth, creating short and long days throughout the year, with a resulting change in the angle and intensity of the sunlight.
| 2015 Solstices and Equinoxes | ||||
|---|---|---|---|---|
| UT | HST | |||
| Perihelion | Jan 4 | 08:59UT | Jan 3 | 22:59HST |
| Vernal Equinox | Mar 20 | 22:45UT | Mar 20 | 12:45HST |
| Summer Solstice | Jun 21 | 16:38UT | Jun 21 | 06:38HST |
| Apehelion | Jul 6 | 12:59UT | Jul 6 | 02:59HST |
| Autumnal Equinox | Sep 23 | 08:20UT | Sep 22 | 22:20HST |
| Winter Solstice | Dec 22 | 04:48UT | Dec 21 | 18:48HST |
| Source: NASA Sky Calendar | ||||