Feb11-2021-at-1905-GMT-New-Moon
New Moon (Chris Vaughan, Starry Night Education)
This Week’s Sky: February 8 to 14, 2021

There’s a new Moon this week, making it an excellent time to check out an open cluster and appreciate bright stars in our sky.

Wednesday, February 10 – Old Moon visits pre-dawn planets (before sunrise)

Old Moon visits pre-dawn planets (Chris Vaughan, Starry Night Education)

Shortly before sunrise in the east-southeastern sky on Wednesday, February 10, observers at southerly latitudes can look for the slim crescent of the old Moon sitting a palm’s width to the right of the bright planet Venus. Much dimmer Jupiter will be positioned a finger’s width to Venus’ left, and Saturn will sit several finger widths above and between the Moon and Venus. The entire grouping will fit within the 6 degrees-wide field of view of binoculars, but ensure that you put your optics away before the Sun rises. Mercury will be positioned less than a fist’s diameter to the left of Venus, too, but it will be difficult to see.

Thursday, February 11 – Bright Venus passes Jupiter (before sunrise)

Bright Venus passes Jupiter (Chris Vaughan, Starry Night Education)

Venus’ closest approach to Jupiter will occur shortly before sunrise on Thursday, February 11. Look just above the east-southeastern horizon before sunrise for the bright planet positioned just to the lower right (or 0.5 degrees to the celestial south of) one-sixth as bright Jupiter. Both planets will fit together in the field of view of binoculars or even a backyard telescope (red circle), but take care to put your optics away before the Sun rises. Faint Saturn will also sit a palm’s width to Venus’ upper right, and much fainter Mercury will be positioned a palm’s width to Venus’ upper left. If Thursday is cloudy, look on Wednesday morning for Venus sitting to Jupiter’s right, and on Friday morning for Venus to Jupiter’s lower left.

Thursday, February 11 – New Moon (at 19:05 GMT)

New Moon (Chris Vaughan, Starry Night Education)

At 19:05 GMT on Thursday, February 11, the Moon will officially reach its new Moon phase. While new, the Moon is travelling between Earth and the Sun. Since sunlight can only reach the far side of the Moon, and the Moon is in the same region of the sky as the Sun, the Moon becomes completely hidden from view for about a day. After new Moon Earth’s celestial night-light will return to shine in the western evening sky.  

Friday, February 12 – Algol dims in brightness (at 7:25 p.m. EST)

Algol dims in brightness (Chris Vaughan, Starry Night Education)

Algol, also designated Beta Persei, is among the most accessible variable stars for skywatchers. For ten hours once every 2 days, 20 hours, and 49 minutes, Algol’s visual brightness dims and re-brightens noticeably. This happens because a companion star orbiting nearly edge-on to Earth crosses in front of the much brighter main star, reducing the total light output we receive. Algol normally shines at magnitude 2.1, similar to the nearby star Almach (aka Gamma Andromedae). While dimmed Algol’s brightness of magnitude 3.4 is almost identical to Rho Persei (or Gorgonea Tertia or ρ Per), the star sitting just two finger widths to Algol’s lower left (or 2.25 degrees to the celestial south). On Friday, February 12 at 7:25 p.m. EST, Algol will be at minimum brightness while sitting high in the western sky. Five hours later Algol will return to its usual magnitude and will be positioned 22 degrees above the western horizon.

Saturday, February 13 – Appreciate the Pleiades (all night)

The Seven Sisters, M45 (Chris Vaughan, Starry Night Education)

At about 7:15 p.m. local time on mid-February evenings, the Pleiades open star cluster, also known as the Seven Sisters and Messier 45, is positioned high in the southern sky. The rest of its home constellation Taurus, the Bull sits below the cluster. Visually, the cluster is composed of medium-bright, hot blue stars named Asterope, Merope, Electra, Maia, Taygeta, Celaeno and Alcyone. In Greek mythology, those characters were the daughters of Atlas, and half sisters of the Hyades. They are indeed related, recently born of the same primordial gas cloud. To the naked eye, only six of the sister stars are usually apparent; their parents Atlas and Pleione are huddled together at the east end of the grouping. Under magnification, hundreds of stars appear. Not surprisingly, many cultures — including Aztec, Maori, Sioux, Hindu and more — have noted this object and developed stories around it. In Japan, it is called Suburu, and forms the logo of the eponymous car maker. Due to its similar shape, the Pleiades are sometimes confused with the Little Dipper.

Sunday, February 14 – Sirius sparkles like a diamond (all night)

Sirius sparkles like a diamond (Chris Vaughan, Starry Night Education)

In mid-February the night sky’s brightest star, Sirius, or Alpha Canis Majoris, reaches its highest point over the southern horizon at around 9:30 p.m. local time. Sirius is a hot, white, A-class star located only 8.6 light-years from Earth — part of the reason for its brilliance. For mid-northern latitude observers, Sirius is always seen in the lower third of the sky, through a thicker blanket of refracting atmosphere. This causes the strong twinkling and flashes of colour the Dog Star is known for.

Chris Vaughan is a science writer, geophysicist, astronomer, planetary scientist and an “outreach RASCal.” He writes Astronomy Skylights, and you can follow him on Twitter at @astrogeoguy. He can also bring his Digital Starlab portable inflatable planetarium to your school or other daytime or evening event. Contact him through AstroGeo.ca to tour the universe together.

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