Conjuction between the Moon and Jupiter

The Moon and Jupiter will make a close approach, passing within 1°20′ of each other.

From Fredericksburg the pair will be visible in the morning sky. They will become accessible at around 21:37, when they rise 7° above your eastern horizon. They will then reach its highest point in the sky at 03:13, 57° above your southern horizon. They will be lost to dawn twilight at around 06:53, 30° above your western horizon.

At the moment of closest approach, the Moon will be at mag -12.4, and Jupiter at mag -2.4, both in the constellation Leo.

The pair will be too widely separated to fit within the field of view of a telescope, but will be visible to the naked eye or through a pair of binoculars.

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NGC 2516 is well placed tomorrow

Across much of the world the open star cluster NGC 2516 in Volans will be well placed for observation. It will reach its highest point in the sky at around midnight local time.

At a declination of -60°52′, it is easiest to see from the southern hemisphere and cannot be seen from latitudes much north of 9°N.

From Washington DC, it will not be observable because it will lie so far south that it never rises above the horizon.

At magnitude 3.8, NGC2516 is tricky to make out with the naked eye except from a dark site, but is visible through a pair of binoculars or small telescope.

 

All articles in this post were found at: in-the-sky.org

Moon at perigee

The Moon will reach the closest point along its orbit to the Earth, and as a result will appear slightly larger than at other times.

The Moon’s distance from the Earth varies because its orbit is not perfectly circular – it is instead slightly oval-shaped, tracing out a path called an ellipse.

As the Moon traverses this elliptical path around the Earth each month, its distance varies by around 10%, between 363,000 km and 405,000 km.

This means that its size in the night sky also varies over the course of each month, by around 13%. It brightness also varies slightly – the Moon appears a little brighter when it is closer to the Earth. In practice, however, this variability is swamped by the much stronger effect that the Moon’s changing phases have over its brightness.

The Moon’s distance varies between perigee (closest approach), apogee (furthest recess) and back again once every 27.555 days – a period of time called an anomalistic month. This is very close to the Moon’s orbital period (27.322 days), but slightly longer. For more information on why these periods don’t exacty match, see In-The-Sky.org’s glossary article for the term month.

As the perigee of 14 January 2016 will occur close to the time of new moon, the moon will appear as no more than a thin crescent.

On this occasion the Moon will pass within a distance of 369,000 km of the Earth, and appear with an angular diameter of 32.31 arcmin. This may be compared to its average size of 31.07 arcmin.

The genuine variation in the Moon’s angular size that is associated with its changing distance from the Earth should not be confused with the Moon illusion – an optical illustion that makes the Moon appear much larger than it really is when it is close to the horizon. The reason why we experience this optical illusion is still hotly debated.

All articles in this post were found at: in-the-sky.org

204P/LINEAR-NEAT reaches its brightest

Comet 204P/LINEAR-NEAT is forecast to reach its brightest, at around mag 12.8. It will lie at a distance of 1.95 AU from the Sun, and at a distance of 0.98 AU from the Earth.

From Washington, D. C. it will be visible between 20:19 and 06:16. It will become accessible at around 20:19, when it rises 24° above your eastern horizon, and then reach its highest point in the sky at 01:20, 72° above your southern horizon. It will become inaccessible at around 06:16 when it sinks to 25° above your western horizon.

For more information about its path across the sky, see In-The-Sky.org’s ephemeris page for comet 204P/LINEAR-NEAT.

This event was automatically generated on the basis of orbital elements published by the Minor Planet Center (MPC), and is updated daily (last update, 11 Jan 2016).

Note that the future positions of comets are typically known with a high degree of confidence, but their brightnesses are often much more unpredictable, since it is impossible to predict with certainty how they will respond as they move closer to the Sun. Magnitude estimates should be assumed to be highly provisional more than a few weeks in advance.

 

All articles in this post were found at: in-the-sky.org

Phrases from Greek myths: A Pandoras box

Another expression originating from Greek myths what we still use is “a Pandora’s box”. This is used to describe something that seems to be harmless but is able to cause a disaster. It is based on a myth about a lady named Pandora, supposedly the first woman that the gods created. Zeus had wanted to use her to punish a man for recieving the fire stolen from Mt. Olympus. Zeus made Pandora an exceptionally beautiful woman, with overflowing curiousity. The god then sent her to earth to be the wife of Epimetheus. Before she left, Zeus gave a a gorgeous box, and told her to never open it. Pandora was happy on earth for a while, however, over time her curiousity was getting stronger. She just had to know whatwas in this box. Just one peek wont hurt anyone.. Pandora thought to herself. So, she opened the box just acrack, but evils and sorrows immediately rushed out of the small box, to fill the earth forever more. She had literally opened “a pandoras box.” Pandora is just one of the many people who gave us these colorful expressions.

 

Astonomy Vocabulary

Apogee

Perigee

Aphelion

Periphilion

AU – The ASTRONOMICAL UNIT

is a unit of length which is approximately equal to the distance of the Earth from the Sun. One astronomical unit is equal to 149.6×109 m, 15.81×10-6 light years, or 4.848×10-6 parsecs.

The astronomical unit is used almost universally for measuring distances between bodies within our Solar System, and when discussing the sizes of planetary systems around other stars. For example, Jupiter orbits the Sun at an average distance of 5.2 AU.

C/2013 US10 (Catalina) reaches its brightest

Comet C/2013 US10 (Catalina) is forecast to reach its brightest, at around mag 5.3. It will lie at a distance of 1.30 AU from the Sun, and at a distance of 0.77 AU from the Earth.

From Odenton (click to change), it will be visible in the dawn sky. It will rise at 22:23 (EST), 9 hours and 5 minutes before the Sun, and attain an altitude of 81° above the eastern horizon before fading from view as dawn breaks at around 06:18.

For more information about its path across the sky, see In-The-Sky.org’s ephemeris page for comet C/2013 US10 (Catalina).

This event was automatically generated on the basis of orbital elements published by the Minor Planet Center (MPC), and is updated daily (last update, 08 Jan 2016).

Note that the future positions of comets are typically known with a high degree of confidence, but their brightnesses are often much more unpredictable, since it is impossible to predict with certainty how they will respond as they move closer to the Sun. Magnitude estimates should be assumed to be highly provisional more than a few weeks in advance.