The AsterNym star registry
Rasalgethi
Rasalgethi: the deep red star of Hercules
deep red · Hercules · α Her
Rasalgethi is a deep red star in the constellation Hercules, one of the stars with a proper name recognised in the IAU Catalog of Star Names. At magnitude 3.08 it is visible to the naked eye under a dark sky.
Most stars in the sky are anonymous points of light. Rasalgethi is not. Some IAU-recognised names are ancient; others were adopted by the IAU only recently. Either way, the star already has a scientific identity, and a dedication attaches a human story to it.
Real star · Personal dedication · Recorded in the AsterNym registry
See what a dedicated page looks like: preview
Rasalgethi at a glance
- Constellation
- Hercules
- Other name
- α Her
- Catalogue number
- HIP 84345
- Distance
- ≈ 360 light-years
- Brightness
- Magnitude 3.08 naked-eye
- Star type
- M5 Ib-II
- Colour
- deep red
- Best seen from
- Almost everywhere on Earth
- Right ascension
- 17h 14m 40s
- Declination
- +14° 23′ 25″
J2000 catalogue coordinates that can be independently cross-checked against astronomical databases. A planetarium app showing coordinates of date will differ slightly, because proper motion and precession move a star’s apparent position over time.
What kind of star is Rasalgethi?
Rasalgethi is a red supergiant. Its surface runs under 4,000°C, which is cool as stars go and why the colour is unmistakably red. Colour in a star is a temperature reading rather than a decoration: the hot ones are blue and the cool ones red, the opposite way round to a kitchen tap.
Its colour is not the whole story. A red star still in the steady part of its life would burn for longer than the universe has yet existed. This one is past that stage, and it is cool at the surface because it has swollen outward, not because it was born this way.
It is a supergiant, which means it has left the stable part of its life and swollen enormously. Put it where the Sun is and its surface would swallow the inner planets. Stars this size do not fade quietly; this one will end as a supernova, and on a human timescale that could be tonight or in a million years.
The light you are looking at is old
The light arriving from Rasalgethi tonight left in about 1666, some 360 years ago. Everything that has happened since, every person you have heard of from the last few centuries, happened while it was in transit.
That delay is the part people find hardest and like most. A star is the one thing you can give someone that was already old before either of you was born and will outlast anything else you could have chosen.
It is comfortably visible without equipment on a decent night.
What does the name Rasalgethi mean?
The term ra's al-jaθiyy or Ras al Djathi appeared in the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, which was translated into Latin as Caput Ingeniculi.
In Chinese astronomy, Alpha Herculis is called 帝座, Pinyin: Dìzuò, meaning 'Emperor's Seat.
Name origin from English Wikipedia. AsterNym does not invent an etymology where none is recorded, and most stars in this catalogue have none: they carry modern names, or a catalogue designation and nothing older.
What could a Rasalgethi dedication represent?
Rasalgethi is especially meaningful for someone who:
- · Deserves something older than any gift shop
- · Marks a beginning, an anniversary or a promise
- · Is remembered every time you look up
- · Has a light you want recorded somewhere permanent
Dedication idea
“For the one I think of when I find Hercules in the sky.”
Where can you see Rasalgethi?
It sits 14° north of the celestial equator, so it clears the horizon everywhere short of latitude 76°S, in practice, every inhabited latitude on Earth. It passes directly overhead at latitude 14°N. It stands highest at midnight in June, so June and July evenings are the best time to look. At magnitude 3.08 it is a naked-eye star only under a dark sky, binoculars make it certain.
Rasalgethi belongs to Hercules.
What does Rasalgethi mean in astrology?
The classical fixed-star tradition: Ptolemy, the medieval Behenian lists, Robson’s 1923 compilation. Is silent on Rasalgethi, and we don’t invent lore where none exists. What astrology can still read is the star’s real position, below.
Projected onto the zodiac the way fixed-star astrology reads any star, Rasalgethi stands at 16° Sagittarius at the J2000 epoch, and the Sun passes that degree around 5 December in the years around 2000. Fixed-star longitude shifts slowly against the tropical zodiac because of precession, about one degree every seventy-two years, so a natal conjunction must be calculated for the birth year rather than read off this J2000 value or a calendar date.
Traditional interpretations, not facts or predictions. The position and dates are computed.
Dedicate Rasalgethi to someone who matters
A flower fades. A card is eventually put away. A star gives your message a place in the sky.
from$29.95a year
Dedicate Rasalgethi →Real star · your message · a page to share
Your Rasalgethi dedication includes
- Your chosen dedication name
- Your personal message
- Rasalgethi's real astronomical coordinates
- A shareable dedication page
- Its location on the AsterNym Galaxy Map
- An optional printable certificate and gift presentation
Rasalgethi keeps its established astronomical name. Your dedication is a personal commemorative record within the AsterNym registry.
Frequently asked questions about Rasalgethi
- What does Rasalgethi mean in astrology?
- The classical fixed-star tradition has no documented meaning for Rasalgethi. Projected onto the zodiac, Rasalgethi stands at 16° Sagittarius, and the Sun passes that degree each year around 5 December.
- Is Rasalgethi the brightest star?
- Rasalgethi shines at magnitude 3.08 · visible to the naked eye on a clear night, one of the few thousand stars with an officially recognised name.
- How far away is Rasalgethi?
- Rasalgethi is approximately 360 light-years from Earth. The light reaching us tonight began its journey around 360 years ago.
- Which constellation contains Rasalgethi?
- Rasalgethi is part of Hercules.
- Can everyone see Rasalgethi?
- It sits 14° north of the celestial equator, so it clears the horizon everywhere short of latitude 76°S, in practice, every inhabited latitude on Earth. It passes directly overhead at latitude 14°N. It stands highest at midnight in June, so June and July evenings are the best time to look. At magnitude 3.08 it is a naked-eye star only under a dark sky, binoculars make it certain.
- Is dedicating Rasalgethi an official astronomical renaming?
- No. Rasalgethi keeps its internationally recognised astronomical name. An AsterNym dedication records your personal name and message in the AsterNym registry without changing the star's scientific identity.
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