July 15

July 15

The Double at the Swan's Beak

Sun Position

The Sun is in Cancer, approaching Leo's boundary, at about +21.6° declination. Northern Hemisphere summer continues; Southern Hemisphere winter nights are long, though Cygnus is low on the northern horizon from mid-southern latitudes.

Sky Highlight

No named meteor shower peaks on July 15. Cygnus passes high overhead at midnight for mid-northern observers in July, making its rich Milky Way field an ideal region for binocular sweeping. From the Southern Hemisphere, Cygnus stays low in the northern sky but Albireo can still be found in a telescope with a clear northern horizon.

Deep Sky Object

NGC 7000, the North America Nebula, an emission nebula in Cygnus roughly 2,200 light-years away. Its distinctive continental shape is unmistakable in photographs but requires extremely dark skies and a wide-field view to detect visually; binoculars under excellent conditions can show the brightest region. A Northern Hemisphere object, difficult from southern mid-latitudes.

Featured Star

Albireo (β Cyg) is 430 light-years away in Cygnus, a gravitationally probable pair of an orange giant (K3II) and a blue main-sequence star (B8Ve). It marks the head of the swan and the foot of the Northern Cross, and the color contrast is visible in any telescope, one of the few deep-sky-quality sights that doesn't require aperture to appreciate.

Around This Date

  • July 15, 1988The Ariane 4 rocket made its maiden flight from Kourou, French Guiana, the workhorse of the European Space Agency's launch program for the following decade, eventually completing 116 missions with a near-perfect success record.
  • June 15, 763 BCEAssyrian scribes recorded a solar eclipse whose date was later used by modern historians to anchor the entire chronology of ancient Mesopotamia, fixing regnal years and events across the ancient Near East with a precision no other ancient record could provide.

The orange and the blue are just physics, but stand at a telescope long enough and physics starts to feel like something else entirely.