Sigma Leonis — Star in Leo
Observe
1Physical Properties
Magnitude
4.05
Spectral Type
B9.5V s
Star Color
Blue-white
(B-V -0.06)
Distance
3,262 ly
3How easy to spot?
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| Equipment | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| Naked eye Naked eye | Easy | Medium+ | Medium |
| 50 mm finder 50mm finder | Easy | Easy | Easy |
| 150 mm telescope 150mm scope | Easy | Easy | Easy |
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
Feb – Apr
(peak: Mar)
5Survey Image
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Explore
7
Size Comparison
Querying VizieR for stellar data…
8
Compare Stars
9
Spectral Classification
10
Hertzsprung-Russell Diagram
Loading HR diagram…
11
Stellar Lifecycle
12
Blackbody Spectrum
13
Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
14
Stellar Fusion
Discover
15
Light Travel Time Machine
16
Relativistic Travel
Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
Explore Nightbase
Related knowledge, tools, and stories — no observation planning required.
Arthur Eddington
1919 eclipse expedition confirming general relativity; first theory of stellar interiors; the Eddington limit
Biography
Leo
Mythology, bright stars, and deep-sky highlights.
Constellation
The Hertzsprung-Russell Diagram — Reading Stars Like a Map
The HR diagram turns the night sky into a physics map: every named star has a spot, every spot tells you mass, age, and fate. A guide for amateur observers.
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