When is the best time to observe Spica?

Spica is best observed from March through May, with peak visibility during April when it transits around midnight in the Northern Hemisphere.

Where is Spica located in the sky?

Spica lies in the constellation Virgo at right ascension 13h 25m and declination -11° 10′.

What telescope do I need to split Spica?

Splitting Spica requires an aperture of roughly 60 mm or larger — the components are separated by about 151.9″ at magnitudes near 1.0. The companion is about 11.0 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Spica — Double Star in Virgo

HIP 65474; Alpha Virginis; 67 Virginis

Magnitude 1.0^m DoubleStar Virgo (Vir) Visible

Star Map + List + Plan

About Spica

Description

Spica is a blue giant of spectral type B1III-IV at magnitude 0.98, the brightest star in Virgo and the 16th brightest in the sky. Located about 250 light-years from Earth, it is actually a close binary system — two hot stars orbiting every 4 days, so close they are distorted into egg shapes by tidal forces. The combined luminosity is about 12,100 times solar.

Observing Tips

Follow the arc of the Big Dipper's handle past Arcturus to 'speed on to Spica' — extending the arc about the same distance. Spica is a brilliant blue-white star low in the spring sky, marking the sheaf of wheat held by the Virgin. It is a useful guide to the Virgo Cluster of galaxies, which lies about 10° to the northwest. Best observed April through July.

History

The name Spica means 'ear of grain' in Latin, referring to the sheaf of wheat in the constellation figure. Hipparchus used observations of Spica around 130 BC to discover the precession of the equinoxes — one of the most important discoveries in ancient astronomy. Copernicus also used Spica to calibrate his observations.

Fun Facts

Spica is a rotating ellipsoidal variable — the two tidally distorted stars present different cross-sections as they orbit, causing tiny brightness changes. Both stars are so hot and massive that they will end their lives as supernovae, possibly leaving behind a double neutron star or even a black hole binary.

Observe

1Physical Properties

Magnitude 0.98

Range 0.96 - 1.00

Period 4.0 days

Variable Type Ellipsoidal Variable

Spectral Type B1IV subgiant

Star Color Blue (B-V -0.23)

Temperature 25412 K

Radius 7.4 R☉

Distance 250 ly

2Position & Identifiers

RA 13h 25m 11.6s

Dec -11° 09' 41.0"

Constellation Virgo (Vir)

HR 5056

HIP 65474

HD 116658

SAO 157923

Bayer Alpha

Flamsteed 67 Vir

Variable ID Alp Vir

SIMBAD Wikipedia

3How easy to split?

Primary 1.0 mag Companion 12.0 mag Separation 151.9″

Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	V. hard+	V. hard+	V. hard
150 mm Newton 150mm Newt.	Medium	Hard+	Hard
Celestron C8 (203 mm SCT) C8 203mm	Medium+	Medium	Hard+

Easy Medium Hard Very hard Impossible

Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs

4Visibility

Set a location in User Settings to see visibility data.

Best season Mar – May (peak: Apr)

5Light Curve

6Multiple Star System Quintuple

Components 5 (quintuple)

Component IDs O

Separation 151.9″

Companion Mag 12.0

Companion Sp B2

Position Angle 33°

Star Colors A: Blue B: Blue

Discoverer BUP 150

Notes

Interferometer indicates visual component A is multiple system. Occultations yield three companions: 3.1v at 0.0025", | 4.5 at 0.05" and 7.5 at 0.5". Combined mag. and colors. Visual component B, 12.0v at 148".

Separation over time

Measured 1879 → 2010 (131 y)

Separation drift 144.4" → 151.9" (+7.50")

Rate +0.0573" / y

PA drift 33° → 33° (+0°, +0.000°/y)

Apparent motion is significant on a human timescale — worth revisiting in a decade.

Measured from the WDS observational archive. No orbital solution has been derived — most likely the period is too long to fit an orbit to the available measurement arc.