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GLENN ROBERTS: Finding the North Star – The Telegram

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A lot of people think that Polaris – the North Star – is the brightest star in the night; nothing could be farther from the truth. When giving a night sky tour to people, as I often get asked to do, and which I am more than happy to do, I have asked them to point out the north star. Invariably, they will point to one of the really bright stars in the night sky, usually Arcturus (mag. -0.05) in Bootes – the Herdsman, Vega in Lyra – the Lyre (mag. +0.02) or Sirius (the actual brightest nighttime star) in Orion – the Hunter (mag. -1.46). When I do point out Polaris to them, they are amazed that it is, in fact so dim (mag. +3.6) and difficult to find. Most people envision Polaris as extremely bright and easy to find; after all, isn’t it used for navigational purposes? Surely, the ancient navigators would have picked a much brighter star to help them find north and, consequently the other three directions.

The selection and importance of Polaris lies not in its brightness, but in its position on the celestial sphere (think of the Earth encased in a clear, outer glass shell) above us relative to the Earth. Polaris lies very close, but not exactly at what is known as “celestial north”. This is the point on the celestial sphere directly above the Earth’s rotational axis, when connected to the Earth’s surface, gives us our geographical reference of “true north”. This differs slightly from “magnetic north”, which we don’t need to worry about for the purpose of this discussion.

The sky area around the “celestial north” (as seen from Earth) is devoid of bright stars. Ancient Greek astronomers and navigators, however, found a star, though dim, that was very close to “celestial north”. Polaris comes from New Latin stella polaris, meaning “pole star”, another name for the North Star. Polaris, although the current North Star, was not always so. In the time of the ancient Egyptians, when the pyramids were being built, the star Thuban in the constellation of Draco – the Dragon was the North Star. In time (though not in our lifetime), other stars in the area around “celestial north” will become the North Star (more about that in another column).

So how do we find the North Star? Here in the northern hemisphere, that is quite easy. The majority of people can recognize and point out the asterism of the “Big Dipper” in the night sky. The Big Dipper is an asterism (think “picture within a picture”) in the constellation of Ursa Major – the Great/Big Bear. Ursa Major is one of several constellations in the night sky which are known as “circumpolar” constellations. This means they circle around the northern pole star Polaris. They are visible on any clear night, as they, at least for us here in the Maritimes, never dip below the northern horizon. Having located the Big Dipper, find the two end stars (sometimes referred to as the “pointer stars”) in the bowl of the dipper, and then connect the two with a straight line (from the bottom star to the top star), continuing the line (about 3x times the distance between the pointer stars) until you come to a semi-bright star sitting all alone; that is Polaris – the North Star. If the sky is dark enough, you will see that it is the end star in the handle of the “Little Dipper” asterism in the constellation of Ursa Minor – the Lesser/Little Bear. Dropping a line from Polaris to the horizon gives your geographical north. Facing this direction and spreading your arms out to the side gives you east on your right, west on your left, and south directly behind.

Jupiter and Saturn continue, as they have all summer, as the prime, naked-eye planets in the late evening sky, though both are setting much earlier (presently around midnight for Jupiter, and shortly thereafter for Saturn) with each passing night. Jupiter can be seen shining brightly at mag. -2.2 in the constellation of Ophiuchus – the Serpent Bearer in the SW sky at twilight. Saturn, at +0.3 mag., shines dimly off to the left of Jupiter, sitting just to the left of the handle of the “teapot” asterism in Sagittarius – the Archer. Both make excellent binocular objects in the crisp, clear night air of September. The remaining “bright planets” (those visible to the naked-eye) — Mars, Mercury and Venus — currently remain lost from sight, as they are too close to the Sun at this time to be visible in the night sky.

Don’t be put off by the lack of bright planets in the night sky this coming week. Once you have looked at Jupiter and Saturn, turn your vision to the multitude of other celestial wonders above you. Just roaming the night sky with a pair of decent binoculars will bring numerous star clusters (both open and globular) into view, not to mention the Moon. Get hold of a good star chart or planisphere, or go online, and get to know your way around the night sky (especially now that you know how to find Polaris – the North Star); there is much to see that will truly amaze you.

Until next time, clear skies.


Events:

Sept 6 – First Quarter Moon.


Glenn K. Roberts lives in Stratford, P.E.I., and has been an avid amateur astronomer since he was a small child. His column, Atlantic Skies, appears every week. He welcomes comments from readers, and anyone who would like to do so is encouraged to email him at glennkroberts@gmail.com.

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Mercury Transit Live Stream – Den of Geek US

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Your Monday is about to get a lot better, especially if you’re on the East Coast. At 7:35 am ET, you’ll get the clearest view of a rare celestial event, as Mercury transits the Sun from our vantage point for the first time since 2016. This is an event we’re only able to witness from Earth about 13 times per century. In fact, the next time you’ll able to watch Mercury cross in front of the Sun is in 2032, which means you probably won’t want to miss it this time around. 

It’ll take Mercury five and a half hours to complete its transit, so you’ll have until 1:04 pm ET to catch the event. Of course, that doesn’t mean you should stare directly at the Sun — protective eyewear is recommended. Check out NASA’s eye safety tips for viewing transits and eclipses. 

For those of you who won’t get a chance to see the event in person, you can watch Mercury’s transit across the Sun in the live stream below:

Video of Mercury Transit 2019 LIVE Stream

Mercury actually completes a full orbit around the Sun every 88 days, but it’s not often that it does so from an Earth-friendly vantage point due to its “eccentric, egg-shaped orbit,” according to NASA. Due to this unusual orbit, the fastest planet in our Solar System, traveling through space at 29 miles per second, can get as close as 29 million miles and as far as 43 million miles from the Sun. For comparison, Earth is about 93 million miles from the star.

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As you’d expect, the first planet in our Solar System can get MUCH hotter than Earth, reaching temperatures higher than 800 degrees Fahrenheit or as cold as minus 290 degrees Fahrenheit since Mercury has no atmosphere with which to retain heat. Basically, don’t expect to find any signs of life on this celestial hellscape.

I leave you with my favorite scene from my favorite science fiction movie, Danny Boyle‘s Sunshine. Chris Evans (before he was Captain America), Cillian Murphy, Rose Byrne, Michelle Yeoh, Cliff Curtis, Hiroyuki Sanada, and the rest of the movie’s killer ensemble cast gather in their spaceship’s observation deck to watch Mercury transit the Sun on their way to reignite the star and save Earth from a chilly death:

Video of "Sunshine" Movie Clip – Approaching Mercury

John Saavedra is an associate editor at Den of Geek. Read more of his work here. Follow him on Twitter @johnsjr9.

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Planet dances with sun | Local News – The Chronicle Journal

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Allan Haney braved cold temperatures at Hillcrest Park on Monday for a front row view of the planet Mercury passing the sun in a rare celestial transit.

He used a pair of binoculars to reflect the sun on a white paper plate to see the tiny black dot that is Mercury as it passed directly between Earth and the sun during the five-and-a-half-hour celestial show that was visible in Canada, the eastern U.S., Central and South America.

The rest of the world, with the exception of Asia and Australia, got just a sampling.

In our solar system, Mercury is the smallest and innermost planet. The next transit will take place in 2032, but North America won’t get another glimpse until 2049.

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Mercury passes across sun’s face in rare 5-hour transit – Global News

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Mini Mercury skipped across the vast, glaring face of the sun Monday in a rare celestial transit.

Stargazers used solar-filtered binoculars and telescopes to spot Mercury — a tiny black dot — as it passed directly between Earth and the sun on Monday.

Planet Mercury is seen as a small silhouette, center left, as it travels across the face of the sun, near capital Nicosia, Cyprus, Monday, Nov. 11, 2019.

Planet Mercury is seen as a small silhouette, center left, as it travels across the face of the sun, near capital Nicosia, Cyprus, Monday, Nov. 11, 2019.


(AP Photo/Petros Karadjias)

The eastern U.S. and Canada got the whole 5 1/2-hour show, weather permitting, along with Central and South America. The rest of the world, except for Asia and Australia, got just a sampling.

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How to watch Mercury’s transit across the sun on Monday

Mercury is the solar system’s smallest, innermost planet. The next transit isn’t until 2032, and North America won’t get another shot until 2049.

This still image from video issued by NASA’s Solar Dynamics Observatory shows Mercury as it passes between Earth and the sun on Monday, Nov. 11, 2019. The solar system’s smallest, innermost planet resembles a tiny black dot during the transit, which began at 7:35 a.m. EST (1205 UTC).

This still image from video issued by NASA’s Solar Dynamics Observatory shows Mercury as it passes between Earth and the sun on Monday, Nov. 11, 2019. The solar system’s smallest, innermost planet resembles a tiny black dot during the transit, which began at 7:35 a.m. EST (1205 UTC).


(NASA Solar Dynamics Observatory via AP)

In Maryland, clouds prevented NASA solar astrophysicist Alex Young from getting a clear peek. Live coverage was provided by observatories including NASA’s orbiting Solar Dynamics Observatory.






4:34
Searching for Mercury


Searching for Mercury

“It’s a bummer, but the whole event was still great,” Young wrote in an email. “Both getting to see it from space and sharing it with people all over the country and world.”

At Cape Canaveral, space buffs got a two-for-one. As Mercury’s silhouette graced the morning sun, SpaceX launched 60 small satellites for global internet service, part of the company’s growing Starlink constellation in orbit.

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© 2019 The Canadian Press

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