Plus (ongoing):        

Wednesdays:

Boston University

Boston, MA.
Open Night at Coit Observatory most Wednesdays 8:30 PM - 9:30 PM. 

617-353-2630
http://www.bu.edu/astronomy/events/public-open-night-at-the-observatory/  

Thursdays (every 3rd Thursday), 8:30 PM:

CfA Public Observatory Night

Harvard-Smithsonian Center for Astrophysics
60 Garden Street

Cambridge, MA 02138
https://www.cfa.harvard.edu/publicevents

Fridays (startng March 3rd!), 8:30 PM

Guilliland Observatory

Museum of Science

1 Science Park

Boston, MA 02114

617-589-0267

https://www.mos.org/public-events/astronomy-after-hours

The Sky Report for the Month of February 2017

            Phases of the Moon:

Planet Visibility:

In Evening (after sunset):

    Neptune, in W 

    Venus, in W

    Mars, in W 

    Uranus, in SW

 At Midnight:

    Uranus, in SW

 In Morning (before sunrise):

    Jupiter, in SW

    Saturn, in SE

    Mercury, in SE 

Comets:

• •     There are no comets brighter than magnitude 8 visible this month.
•          

Meteors:      

•     
  •     There no significant meteor showers in February.
      

Mercury, Saturn, and Jupiter grace the morning sky at midmonth.

On the 15th, the waning gibbous Moon is just 3° to the upper right of Jupiter.

      An annular solar eclipse occurs on February 26th. As seen from a narrow swath of territory passing over southern Chile and Argentina, the South Atlantic, and southern Africa, the Moon will move directly in front of the Sun. However, it will be too distant in its orbit and its disk will be too small to completely cover the Sun’s disk. The brightness of the remaining light from the solar disk will prevent the many marvelous and subtle effects of a total solar eclipse – such as the delicate corona, “Baily’s Beads”, and the “Diamond Ring” – from appearing. Still, annular eclipses are often picturesquely described as “Ring of Fire” eclipses.

 (February 26, 2017, 6:38 AM EST).

Mars and Uranus approach each other to within 0.6° on the 26th.

That angular distance is barely larger than the size of the Full Moon (shown as yellow circle).  

 The Big Eyes   

Have you gotten a new telescope recently – perhaps as a holiday gift? How large was it? (We measure the size of a telescope not by its length but by the diameter of its “objective” – whether it’s a lens or a mirror). Chances are that it was in the size range of 6” (~150 mm), 8” (~200 mm) or – if Santa was generous to you -10” (~250 mm in diameter). How does your telescope compare to others?

The first telescope used to observe the sky was that used by Galileo around 1609. It is estimated to have been about 0.62” (15 mm) in diameter. Moreover, its optics were crude. Still, that instrument allowed Galileo to discover craters on the Moon, the phases of Venus, the four large moons of Jupiter, and the fact that the Milky Way is composed of innumerable faint stars. No matter how small your telescope is, it should be able to observe all these phenomena and more.

In the interval since, telescopes have gotten larger. How much larger?

Some of the most significant discoveries of the 20th century – such as the facts that our galaxy is one of many and that the Universe is expanding - were made by the 100” (2.54 meter) telescope on Mt. Wilson outside Los Angeles. It was soon superseded by the 200” (5.1 meter) telescope on Mt. Palomar.

The next major advance was the construction of the twin Keck telescopes in Mauna Kea in Hawai’i. Each hosts a mirror composed of 36 individual mirror segments with a collective diameter of 10 meters. Keck 1 was completed in 1993, and Keck 2 in 1996.

Incidentally, the Hubble Telescope, launched in 1990, has a diameter of “only” 2.54 meters; its superior performance is due not to its size, but to the fact that it orbits far above Earth’s distorting atmosphere. The upcoming James Webb Space Telescope, to be launched in 2018, has a segmented 6.5 meter-diameter mirror.

Since then the race for ever larger apertures has continued. The 36-segment, 10.4-meter Gran Telescopio Canarias has been operating on La Palma in the Canary Islands since 2009.