January 25, 2016 - Mutual Attraction on a Galactic Scale

Mutual Attraction on a Galactic Scale  These two galaxies really have a hold on each other—gravitationally speaking, that is. The neighboring galaxies NGC 3166 (top) and NGC 3169 (bottom) are close enough to have a gravitational pull on each other that’s stretching and shredding their star and dust lanes apart. The galaxies are steadily moving closer together and will eventually merge entirely. These galactic partners are located comparatively nearby—a mere 70 million light-years away within the southern constellation Sextans. A relatively “new” constellation, Sextans was named in 1687 by the Polish astronomer Johannes Hevelius, who was born 405 years ago this week. Hevelius discovered four comets, identified the Moon’s libration (sideways wobble), and spent years charting the lunar surface.

Image credit: ESO / Igor Chekalin

Weekly Calendar

January 25 - January 31, 2016

Holidays - Sky Events - Space History

Moon phase Monday 25

Mercury appears stationary

1736: Joseph Lagrange born
1962: NASA authorizes Saturn V rocket
1983: IRAS launched
1994: Clementine spacecraft launched
2004: Mars Exploration Rover Opportunity lands

Moon phase Tuesday 26

Moon phase Wednesday 27

Jupiter 1.4° north of Moon

1829: Isaac Roberts born, pioneer astrophotographer
1967: Apollo 1 astronauts Grissom, White, and Chaffee die in cockpit fire on launch pad during test

Moon phase Thursday 28

1611: Johannes Hevelius born
1986: Space Shuttle Challenger explodes, 7 astronauts die

Moon phase Friday 29

1964: SA-5 launched, first Saturn I Block 2 rocket
1989: Phobos 2 enters orbit around Mars

Moon phase Saturday 30

Moon at apogee

1964: Ranger 6 launched

Moon phase Sunday 31

Last Qtr Moon 10:28 PM ET

1958: Explorer 1 launched
1961: Mercury Redstone 2 suborbital flight with chimpanzee Ham
1966: Luna 9 launched
1971: Apollo 14 launched
1985: ESA approves the Columbus program

Suggestions for new history dates or better links? Corrections for errors on this page? Please e-mail me.