diff --git a/src/main/java/com/planetrush/planetrush/planet/service/PlanetServiceImpl.java b/src/main/java/com/planetrush/planetrush/planet/service/PlanetServiceImpl.java
index a73aa54..29f68e9 100644
--- a/src/main/java/com/planetrush/planetrush/planet/service/PlanetServiceImpl.java
+++ b/src/main/java/com/planetrush/planetrush/planet/service/PlanetServiceImpl.java
@@ -1,7 +1,6 @@
 package com.planetrush.planetrush.planet.service;
 
 import java.time.LocalDate;
-import java.time.LocalDateTime;
 import java.time.temporal.ChronoUnit;
 import java.util.List;
 import java.util.stream.Collectors;
@@ -264,35 +263,16 @@ public List<GetMainPlanetListDto> getMainPlanetList(Long memberId) {
 			.orElseThrow(() -> new MemberNotFoundException("Member not found with ID: " + memberId));
 		List<GetMainPlanetListVo> planetList = planetRepositoryCustom.getMainPlanetList(member);
 		return planetList.stream()
-			.map(this::convertToDto)
+			.map(vo -> GetMainPlanetListDto.builder()
+				.planetId(vo.getPlanetId())
+				.planetImgUrl(vo.getPlanetImgUrl())
+				.name(vo.getName())
+				.status(vo.getStatus())
+				.lastDay(planetValidator.checkLastDay(vo))
+				.build())
 			.toList();
 	}
 
-	/**
-	 * 마지막 인증 날짜 혹은 행성 시작 날짜와 오늘 날짜를 비교해 lastDay 변수에 담아줍니다.
-	 * @param vo GetMainPlanetListVo
-	 * @return GetMainPlanetListDto
-	 */
-	private GetMainPlanetListDto convertToDto(GetMainPlanetListVo vo) {
-		LocalDate today = LocalDate.now();
-		LocalDateTime lastVerifyDate = vo.getLastVerifyDate();
-		LocalDate planetStartDate = vo.getPlanetStartDate();
-		boolean isLastDay = false;
-		long daysBetween = ChronoUnit.DAYS.between(planetStartDate, today);
-		isLastDay = daysBetween >= 2;
-		if (lastVerifyDate != null) {
-			daysBetween = ChronoUnit.DAYS.between(lastVerifyDate.toLocalDate(), today);
-			isLastDay = daysBetween >= 3;
-		}
-		return GetMainPlanetListDto.builder()
-			.planetId(vo.getPlanetId())
-			.planetImgUrl(vo.getPlanetImgUrl())
-			.name(vo.getName())
-			.status(vo.getStatus())
-			.lastDay(isLastDay)
-			.build();
-	}
-
 	/**
 	 * {@inheritDoc}
 	 *
diff --git a/src/main/java/com/planetrush/planetrush/planet/service/PlanetValidator.java b/src/main/java/com/planetrush/planetrush/planet/service/PlanetValidator.java
index 6e1f18b..35e184a 100644
--- a/src/main/java/com/planetrush/planetrush/planet/service/PlanetValidator.java
+++ b/src/main/java/com/planetrush/planetrush/planet/service/PlanetValidator.java
@@ -13,6 +13,7 @@
 import com.planetrush.planetrush.planet.exception.ResidentOverflowException;
 import com.planetrush.planetrush.planet.repository.ResidentRepository;
 import com.planetrush.planetrush.planet.repository.custom.ResidentRepositoryCustom;
+import com.planetrush.planetrush.planet.service.vo.GetMainPlanetListVo;
 
 import lombok.RequiredArgsConstructor;
 
@@ -25,6 +26,9 @@ public class PlanetValidator {
 	private static final int MAX_RESIDENT_LIMIT = 9;
 	private static final int MAX_CHALLENGE_START_OFFSET = 14;
 
+	private static final int LAST_DAY_FROM_PLANET_START_DAYS = 2;
+	private static final int LAST_DAY_AFTER_VERIFY_DAYS = 3;
+
 	/**
 	 * 가입 가능한 최대 챌린지 수를 초과하는지 검사합니다.
 	 * @param member
@@ -59,4 +63,26 @@ public void checkStartDate(LocalDate startDate) {
 		}
 	}
 
+	/**
+	 * 마지막 인증 날짜 혹은 행성 시작 날짜와 오늘 날짜를 비교해 결과를 반환합니다.
+	 * @param vo GetMainPlanetListVo
+	 * @return 행성에서 탈퇴 당하기 직전인지 여부
+	 */
+	public boolean checkLastDay(GetMainPlanetListVo vo) {
+		LocalDate today = LocalDate.now();
+		if (vo.getLastVerifyDate() != null) {
+			return isLastDayAfterVerify(vo.getLastVerifyDate().toLocalDate(), today);
+		}
+		return isLastDayFromPlanetStart(vo.getPlanetStartDate(), today);
+	}
+
+	private boolean isLastDayFromPlanetStart(LocalDate planetStartDate, LocalDate today) {
+		long daysPassed = ChronoUnit.DAYS.between(planetStartDate, today);
+		return daysPassed >= LAST_DAY_FROM_PLANET_START_DAYS;
+	}
+
+	private boolean isLastDayAfterVerify(LocalDate lastVerifyDate, LocalDate today) {
+		long daysPassed = ChronoUnit.DAYS.between(lastVerifyDate, today);
+		return daysPassed >= LAST_DAY_AFTER_VERIFY_DAYS;
+	}
 }